Cancer Incidence Rates in Eddy and Lea Counties

New Mexico, 1970-1994

RESULTS AND DISCUSSION

Assessments of cancer sites are arranged alphabetically, with the exception of Childhood - All Sites and Childhood - Leukemia which are listed last. Figures and tables describing the spatial and temporal variation of cancer incidence rates in New Mexico, Eddy County, and Lea County, are presented at the end of this report. In the following descriptions of spatial variations, only those comparisons are presented for which the incidence rates have non-overlapping confidence intervals. Those incidence rates that are among the ten highest among counties in New Mexico are also identified. As previously noted, consideration of confidence intervals is critical to accurate interpretations of incidence rate estimates. In discussions of temporal variation, the patterns presented are descriptive in nature, since no statistical analyses or confidence bounds were generated for the temporal data. For some cancer sites, a section is included describing factors that have previously been identified as being associated with certain patterns of cancer incidence rates.

Cancer of All Sites

Although incidence and mortality rates vary widely for specific cancers, cancers of the lung and bronchus, breast, prostate, and colon and rectum account for over half of all cancer cases and cancer deaths in the US. The leading cancers diagnosed in New Mexico in 1993 (invasive only) among males and females are presented in Figures 1,2, and 3. Statewide, the leading cancers of men include prostate, lung, and colon, and the leading cancers of women include breast, lung, and colon. In general in New Mexico, men have higher incidence rates than women, and non-Hispanic whites have higher incidence rates than Hispanic whites.

Trends in cancer incidence for all sites are associated with many factors (NCI 1993), including tobacco and alcohol use, nutrition and diet, exposure to sunlight, hormone treatments, occupational exposures to toxic chemicals, exposure to ionizing radiation, and certain viruses (ACS 1995). Smoking alone, however, may account for 40% of all cancer deaths in men and 20% in women in the US (NCI 1993).

Nationally, cancer incidence rates for all sites combined have increased steadily over the last two decades, from approximately 320 per 100,000 in 1973 to 389 in 1990 (NCI 1993). In New Mexico, cancer incidence rates of all sites combined have also increased during the period studied, from approximately 280 per 100,000 in 1971 to 330 in 1993. Still, cancer incidence and mortality is relatively low in New Mexico; in 1990, the incidence rate for cancer of all sites among New Mexicans was approximately 350 per 100,000, about 10% lower than the US rate, and between 1986 and 1990, New Mexico had the fourth lowest rate of deaths from cancer in the US (about 15% lower than the total US rate) (NCI 1993).

Spatial Variation

Spatial variation of incidence rates for cancers of all sites, for the period between 1970 and 1992, among residents of New Mexico, Eddy County, and Lea County, is presented in Tables 5, 6 and 7.

Non-Hispanic Whites: During the period studied, the incidence rate for cancer of all sites among non-Hispanic white males and females combined was 341 per 100,000 statewide, and ranged from a low of 246 in Harding County to a high of 458 in Rio Arriba County. The incidence rate among non-Hispanic white males and females residing in Lea County was below the corresponding statewide rate. Incidence rates for cancer of all sites among non-Hispanic white males residing in Eddy and Lea counties were higher than among non-Hispanic white females: 386 vs. 298 in Eddy County and 302 vs. 222 in Lea County. Incidence rates for cancer of all sites among non-Hispanic white males and among non-Hispanic white females in Eddy County were higher than the corresponding rates in Lea County.

Hispanic Whites: During the period studied, the incidence rate for cancer of all sites among Hispanic white males and females combined was 248 per 100,000 statewide, and ranged from a low of 134 in Harding County to a high of 284 in Valencia/Cibola counties. The incidence rates among Hispanic white males and Hispanic white females residing in Lea County were well below the corresponding statewide rates. The incidence rate of cancer of all sites among Hispanic white females was higher in Eddy County than in Lea County.

Temporal Variation

Temporal variation of incidence rates for cancer of all sites, for the period between 1970 and 1994, among residents of New Mexico, Eddy County and Lea County is presented in Figures 4,5 and 6.

By Sex: Statewide, incidence rates for cancer of all sites appear to have increased among males during the period studied, from approximately 310 per 100,000 in 1971 to over 400 in 1993, and slightly less among females, from approximately 250 per 100,000 in 1971 to 280 in 1993. Statewide cancer incidence rates among both sexes began decreasing after 1990 (more sharply for males, possibly due to the similar pattern of decreasing prostate cancer incidence rates), and rates were higher among males than among females. In Eddy and Lea counties, males and females exhibited similar magnitudes and fluctuation of cancer incidence rates, but rates were higher among males than among females. In Eddy County, the magnitude and pattern of cancer incidence rates was similar to statewide rates, increasing among males from approximately 330 per 100,000 in 1971 to 420 in 1993; increasing less among females, from approximately 300 in 1971 to 310 in 1993; and decreasing in the early 1990s. In Lea County, incidence rates for cancer of all sites among both sexes combined were lower than statewide rates and followed a different pattern. Rates among males increased, but were more variable over time than for Eddy County, ranging from a low of approximately 240 per 100,000 in 1983 to a high of 400 in 1992. Rates among females decreased from approximately 200 per 100,000 in 1971 to 170 in 1993.

By Ethnicity: Statewide, incidence rates for cancer of all sites have increased among non-Hispanic whites from approximately 310 per 100,000 in 1971 to 375 in 1993, and among Hispanic whites from approximately 210 per 100,000 in 1971 to 290 in 1993. Cancer incidence rates for non-Hispanic whites in New Mexico were higher than those for Hispanic whites for the entire period of study. In Eddy and Lea counties, cancer incidence rates among non-Hispanic whites exhibited the strongest trends in magnitude and fluctuation of rates, and rates for Hispanic whites were more variable over time than rates for non-Hispanic whites. In Eddy County, the pattern and magnitude of cancer incidence rates among both ethnicities were similar to that of statewide rates during the period studied. Cancer incidence rates increased among non-Hispanic whites from approximately 325 per 100,000 in 1971 to 390 in 1993, and among Hispanic whites from approximately 230 per 100,000 in 1971 to 275 in 1993. In Lea County, cancer incidence rates among both ethnicities were lower than statewide rates, and did not follow the same pattern. The rates for non-Hispanic whites in Lea County increased only slightly during the period studied, from approximately 250 per 100,000 in 1971 to 275 in 1993. Although these rates peaked in 1990 and then dropped, they also peaked and then dropped around 1978. Rates among Hispanic whites residing in Lea County increased slightly during the period studied, from approximately 180 per 100,000 in 1971 to 190 in 1993, but they varied widely, with a low of approximately 100 per 100,000 in 1973 and a high of 310 around 1978.

Factors Affecting Rates: Statewide cancer incidence rates may be lower than national rates because the population in New Mexico is comprised of higher proportions of ethnic groups, such as Hispanic whites and Native Americans, who have lower cancer incidence, and of lower proportions of ethnic groups, such as blacks, who have higher cancer incidence. The pattern of statewide incidence rates for all types of cancer combined is primarily a reflexion of changes in incidence rates for prostate and female breast cancer.

Bladder Cancer

In New Mexico, bladder cancer was the fourth most frequently occurring cancer in men in 1993 (Figure 1), and was estimated to be the fifth most frequently occurring cancer for both sexes combined in 1995 (ACS 1995).

Men are diagnosed with this cancer four times more frequently than women (NCI 1993). Risk factors include smoking; exposure to certain chemicals, including arylamines and polycyclic aromatic hydrocarbons; exposure to ionizing radiation; consumption of high-fat foods, pork, and beef; frequent urinary tract infections; and urination habits. Smoking alone may be responsible for approximately half the bladder cancers diagnosed in men and one third of the bladder cancers diagnosed in women. Smoking and occupational exposures, however, do not fully account for the disproportionate number of cases diagnosed in men, suggesting that bladder cancer may also be affected by physical gender differences.

Nationally, incidence rates for invasive and in situ bladder cancer have increased slightly over the last two decades, from 14.6 per 100,000 in 1973 to 16.7 in 1990 (NCI 1993). In New Mexico, incidence rates for invasive and in situ bladder cancer are lower than US rates, increasing slightly over the study period, from approximately 11 per 100,000 in 1971 to 12.5 in 1993 (Figure 7), but decreasing overall beginning around 1987.

Spatial Variation

Spatial variation of incidence rates for bladder cancer, for the period between 1970 and 1992, among residents of New Mexico, Eddy County, and Lea County, is presented in Tables 8, 9 and 10.

Non-Hispanic Whites: During the period studied, the incidence rate for bladder cancer among non-Hispanic white males and females combined was 15.9 per 100,000 statewide, and ranged from a low of 4.3 in Harding County to a high of 23.4 in Sandoval County. The incidence rate among non-Hispanic whites residing in Lea County was below the corresponding statewide rate. Bladder cancer incidence rates in Eddy and Lea counties were higher among non-Hispanic white males than non-Hispanic white females: 24.8 vs. 5.2 (per 100,000) in Eddy County and 19.6 vs. 4.1 (per 100,000) in Lea County.

Hispanic Whites: During the period studied, the incidence rate for bladder cancer among Hispanic white males and females combined was 7.3 per 100,000 statewide, and ranged from a low of no cases in Catron County to a high of 12.5 in Union County. Hispanic white females had an incidence rate of 8.6 per 100,000 (the third highest county rate among Hispanic white females in New Mexico).

Temporal Variation

Temporal variation of incidence rates for bladder cancer, for the period between 1970 and 1994, among residents of Eddy County and Lea County is presented in Figures 8 and 9.

By Sex: Statewide, bladder cancer incidence rates increased among males during the period studied, from approximately 17.5 per 100,000 in 1971 to 22 in 1993, but remained about the same for females, at just over 5 per 100,000. Rates among males were 3 to 4 times higher than rates among females during the study period. In addition, statewide incidence rates among males increased in a two-step pattern, one occurring after 1974 and another after 1985. In Eddy and Lea counties, the pattern of fluctuations of bladder cancer incidence rates were similar between males and females, but rates among males were higher than among females. In Eddy County, bladder cancer incidence rates were generally higher than statewide incidence rates during the period studied, and followed a different pattern than statewide rates. Incidence rates among males residing in Eddy County increased, from approximately 21 per 100,000 in 1971 to 28 in 1993, but were unstable, with peaks in incidence around 1982 and 1992. Rates among females residing in Eddy County decreased during the period studied, from approximately 8 per 100,000 in 1971 to 4 in 1993. In Lea County, bladder cancer incidence rates among males increased from approximately 10 per 100,000 in 1971 to 29 in 1993, and followed the same pattern as statewide rates. Rates among females residing in Lea County did not change substantially between 1970 and 1994, remaining at approximately 4 or 5 per 100,000; however, the rates varied during the years studied, ranging from a low of approximately 1 per 100,000 between 1984 and 1985 to a high of 7 in 1993, with no cases reported for several years.

By Ethnicity: Statewide, bladder cancer incidence rates appear to have increased slightly during the period studied among non-Hispanic whites, from approximately 14 per 100,000 in 1971 to 16 in 1993, and among Hispanic whites, from approximately 6 per 100,000 in 1971 to 8 in 1993. In general, rates were higher among non-Hispanic whites than among Hispanic whites. However, because of the comparatively small number of cases reported, bladder cancer incidence rates for Hispanic whites in Eddy and Lea counties were highly variable, with large confidence internals. The variations in magnitude of incidence rates for bladder cancer in these two counties were greatest among non-Hispanic whites.

Factors Affecting Rates: About one-third of bladder cancers among women may be associated with cigarette smoking, with other risk factors accounting for smaller portions (NCI 1993). The overall increase and pattern of bladder cancer incidence for males in New Mexico may be due to NMTR staff training resulting in better clinical diagnosis of bladder cancers, better identification of bladder cancers on pathology reports, clearer tumor registry abstracting and coding guidelines after 1984, and NMTR coding changes in 1974 and 1984 that resulted in more complete identification of in situ bladder cancers.

Bone Cancer

Bone cancer is uncommon in the US; about 2,100 new invasive bone cancers are diagnosed per year (Rosenberg 1994), accounting for .5% of malignant tumors (Mettler 1995). In 1994 in New Mexico, 17 new cases of in situ and invasive bone cancer were diagnosed, accounting for only 0.3% of all cancers (NMTR 1996).

In general, as age increases, males are diagnosed with this cancer slightly more frequently than females (NCI 1993). Risk factors for bone cancer include Paget's disease, exposure to ionizing radiation, exposure to certain chemicals, metal prostheses, localized bone death, chronic bone infections, and genetic mutations (Rosenberg 1994).

Nationally, the incidence rate of invasive bone and joint cancer for the period between 1986 and 1990 was 0.8 per 100,000 (NCI 1993). In New Mexico, bone cancer incidence rates decreased slightly during the period studied, from approximately 1.3 per 100,000 in 1971 to 1.0 in 1993 (Figure 10). In general, incidence rates of bone cancer in New Mexico appear to be comparable with US rates: between 1986 and 1990, the incidence rate for bone cancer among New Mexicans was less than 1.0 per 100,000.

Spatial Variation

Spatial variation of incidence rates for bone cancer, for the period between 1970 and 1992, among residents of New Mexico, Eddy County, and Lea County, is presented in Tables 11,12 and 13.

Non-Hispanic Whites: During the period studied, the incidence rate for bone cancer among non-Hispanic white males and females combined was 0.9 per 100,000 statewide, and ranged from a low of no cases in Catron, De Baca, Guadalupe, Harding, Hidalgo, Lincoln, Mora, Rio Arriba, Socorro, Taos, and Torrance counties to a high of 2.5 in Union County. Hispanic Whites: During the period studied, the incidence rate for bone cancer among Hispanic white males and females combined was 0.9 per 100,000 statewide, and ranged from a low of no cases in Catron, De Baca, Guadalupe, Harding, Lea, Lincoln, Los Alamos, Mora, Otero, Quay, Torrance, and Union counties, to a high of 3.4 in Roosevelt County.

Temporal Variation

Temporal variation of incidence rates for bone cancer, for the period between 1970 and 1994, among residents of Eddy County and Lea County is presented in Figures 11 and 12.

By Sex: Statewide, bone and joint cancer incidence rates for males appeared to be about the same as for females during the period studied, ranging from a low of approximately 0.7 per 100,000 to a high of 1.5 for several years. In Eddy County, few bone cancer cases were reported during the period studied for either sex, and in Lea County no cases of bone and joint cancer were reported for females. Although trends are difficult to assess because of the small numbers of cases reported, bone and joint cancer incidence rates among both sexes appear to be similar to statewide rates.

By Ethnicity: Statewide, bone and joint cancer incidence rates among non-Hispanic whites appear to be about the same as among Hispanic whites during the period studied. In Eddy County, few bone cancer cases were reported for non-Hispanic whites and Hispanic whites during the period studied, and in Lea County, no cases of bone and joint cancer were reported for Hispanic whites.

Brain and Nervous System Cancers

Brain and other nervous system cancers are relatively uncommon in the US; the NCI estimated that 17,500 new brain and other nervous system cancers were diagnosed in the US in 1993 (NCI 1993). In 1994 in New Mexico, 94 in situ and invasive brain cancers and 3 in situ and invasive nervous system cancers were diagnosed, comprising about 1.4% of total cancers (NMTR 1996).

Males are diagnosed with this cancer 1.5 times more often than females (NCI 1993). Risk factors for brain cancer are not well understood. However, possible risk factors include exposure to ionizing and electro-magnetic radiation, exposure to certain chemicals such as organic solvents and pesticides, and having a family history of brain cancer.

Nationally, brain and other nervous system cancer incidence rates have increased slightly over the last several decades, from 5 per 100,000 in 1973 to 6.3 in 1990 (NCI 1993). In New Mexico, incidence rates for brain and other nervous system cancer increased slowly from 1970 to the mid-1980s, and then began decreasing (Figure 13). While rates have not substantially changed overall from 1970 to 1994, they have varied for individual years, ranging from a low of approximately 4 per 100,000 in 1980 to a high of 5.5 in 1986. Statewide rates for males and females combined were generally lower during the period studied than comparable rates for the US (NCI 1993).

Spatial Variation

Spatial variation of incidence rates for brain and other nervous system cancer, for the period between 1970 and 1992, among residents of New Mexico, Eddy County, and Lea County, is presented in Tables 14, 15 and 16.

Non-Hispanic Whites: During the period studied, the incidence rate of brain and other nervous system cancers among non-Hispanic white males and females combined was 5.6 per 100,000 statewide, and ranged from a low of no cases in Harding County to 13.6 in Rio Arriba County. Incidence rates among non-Hispanic whites in Eddy and Lea counties were below the corresponding statewide rates.

Hispanic Whites: During the period studied, the incidence rate for brain and other nervous system cancers among Hispanic white males and females combined was 3.8 per 100,000 statewide, and ranged from a low of no cases in Catron, Roosevelt, and Union counties, to a high of 13.4 in Los Alamos County. Incidence rates of brain and other nervous system cancers were below corresponding statewide rates among Hispanic white males in Eddy and Lea counties.

Temporal Variation

Temporal variation of incidence rates for brain and other nervous system cancer, for the period between 1970 and 1994, among residents of Eddy County and Lea County is presented in Figures 14 and 15.

By Sex: Statewide, incidence rates of brain and other nervous system cancers increased slightly among males during the period studied, from approximately 4.3 per 100,000 in 1971 to 5.5 in 1993, and decreased slightly among females from approximately 4.5 per 100,000 in 1971 to 3.3 in 1993. Incidence rates for brain and other nervous system cancer among males were generally higher than among females statewide, but in Eddy and Lea counties, rates were similar among both sexes. In Eddy County, brain and other nervous system cancer incidence rates decreased slightly among males and increased slightly among females. In Lea County, the incidence rates decreased slightly among males, and did not substantially change overall among females. However, rates among both sexes in Eddy and Lea counties varied widely (by as much as 7 times).

By Ethnicity: Statewide, incidence rates of brain and other nervous system cancer did not substantially change overall among non-Hispanic whites or Hispanic whites during the period studied. In general, incidence rates among non-Hispanic whites were higher than among Hispanic whites. For many of the years studied, no cases of brain or other nervous system cancer among Hispanic whites were reported in either county.

Factors Affecting Rates: Increases in diagnoses of brain cancer between 1970 and 1994, especially among older people, may be due to new medical imaging techniques (NCI 1993). These techniques include Computerized Axial Tomography (CAT), in use in the mid-1970s, and Nuclear Magnetic Resonance Imaging (NMRI), in use in the late 1980s. Before the development of these techniques, some deaths from brain tumors may have been misclassified as strokes.

Breast Cancer (Female)

Breast cancer is the leading cancer among women in the US and in New Mexico. In New Mexico in 1993, breast cancer was three times more common than the next most commonly diagnosed cancer in women (lung) (Figure 1).

Risk factors for breast cancer include a family history of breast cancer; hormonal factors such as early age at menarche, late age at menopause, never giving birth or breastfeeding, first giving birth at a late age, and exposure to estrogen (such as in oral contraceptives or therapies related to menopause); poor dietary habits including low vegetable consumption; social factors such as higher education and socioeconomic level; and exposure to ionizing radiation (NCI 1993; ACS 1995; Mettler 1995).

Nationally, incidence rates of invasive breast cancer have increased over the last two decades, from approximately 82.4 per 100,000 in 1973 to 109 in 1990 (NCI 1993). However, this rise has not been steady, with a spike around 1974, another large increase between 1980 and 1987, and falling rates from 1988 to 1990. In New Mexico, incidence rates of breast cancer were slightly lower than, or comparable to, US rates, increasing from approximately 68 per 100,000 in 1971 to 92 in 1993 (Figure 16). Like US rates, statewide rates also fell, but began a few years later, in 1991.

Spatial Variation

Spatial variation of incidence rates for breast cancer, for the period between 1970 and 1992, among females residing in New Mexico, Eddy County, and Lea County, is presented in Table 17.

Non-Hispanic Whites: During the period studied, the statewide incidence rate of breast cancer among non-Hispanic white females was 94.0 per 100,000 statewide, and ranged from a low of 24.6 in Mora County to a high of 134 in Rio Arriba County. Breast cancer incidence rates among non-Hispanic white females residing in Eddy and Lea counties were below this statewide rate. In both counties, breast cancer incidence rates were higher among non-Hispanic white females than among Hispanic white females.

Hispanic Whites: During the period studied, the statewide incidence rate of breast cancer among Hispanic white females was 56.8 per 100,000 statewide, and ranged from a low of 30.0 in De Baca County to a high of 91.0 in Los Alamos County. The breast cancer incidence rate among Hispanic white females residing in Lea County was below the statewide rate.

Temporal Variation

Temporal variation of incidence rates for breast cancer, for the period between 1970 and 1994, among females residing in Eddy County and Lea County is presented in Figures 17 and 18. Females: Statewide, breast cancer incidence rates increased overall during the period studied, from approximately 68 per 100,000 in 1971 to 92 in 1993, but began to level off in 1990, and fall in 1991. In Eddy County, breast cancer incidence rates increased from approximately 72 per 100,000 in 1971 to 97 in 1993, and were comparable in magnitude to, and generally followed the pattern of, statewide rates. In Lea County, breast cancer incidence rates did not substantially change overall between 1970 and 1994, did not follow the pattern of statewide rates, and were close to one-half the magnitude of statewide rates. Incidence rates of breast cancer varied widely among females in both counties during the period studied.

By Ethnicity: Statewide, breast cancer incidence rates appear to have increased among non-Hispanic white females, from approximately 83 per 100,000 in 1971 to 109 in 1993, and among Hispanic white females, from approximately 40 per 100,000 in 1971 to 75 in 1993. Rates among non-Hispanic whites were higher than rates among Hispanic whites during the entire study period, and comparable to US rates. Rates among both ethnic groups appear to follow the statewide pattern. County-level breast cancer incidence rates were more variable during the study period (especially for Hispanic whites). In Eddy County, breast cancer incidence rates among non-Hispanic white females increased during the period studied, from approximately 68 per 100,000 in 1971 to 105 per 100,000 in 1993. Incidence rates of breast cancer among Hispanic white females residing in Eddy County decreased overall during the period studied, from approximately 80 per 100,000 in 1971 to 65 per 100,000 in 1993, but fluctuated widely, so that a clear downward trend was not obvious. In Lea County, breast cancer incidence rates among Hispanic whites also varied widely, jumping from approximately 4 per 100,000 in 1980 to 65 per 100,000 in 1990. Breast cancer incidence rates among non-Hispanic whites residing in Lea County increased overall during the period studied, from approximately 50 per 100,000 in 1971 to 55 per 100,000 in 1993, but varied for individual years between 1970 and 1994.

Factors Affecting Rates: A spike in SEER (national) breast cancer incidence rates in 1974 have been suggested to have been related to the publicity surrounding the breast cancer surgeries of several prominent women (NCI 1993). The increase may also have been due to increases in early diagnosis resulting from the use of mammography screening. Cancers which normally would have been diagnosed during this period with techniques other than mammography may have been diagnosed earlier with mammography.

Colon Cancer

Colorectal cancer is the fourth most frequently diagnosed cancer in the US. In 1993 in New Mexico, invasive colon cancer (excluding rectum) was the third most frequently diagnosed cancer in both men and women (Figure 4).

Men are diagnosed with this cancer slightly more frequently than women (NCI 1993). Risk factors include having a high-fat, low-fiber, low-nutrition diet; inflammatory bowel disease; exposure to ionizing radiation; and a family history of colorectal cancer (NCI 1993; Mettler 1995).

Nationally, incidence rates for invasive colon cancer have increased over the last two decades, from 31.8 per 100,000 in 1973 to 34.1 in 1990 (NCI 1993). Despite this overall increase, colon cancer incidence rates have been decreasing during the last decade, dropping from a high of 37.7 per 100,000 in 1985. Incidence rates of colon cancer of New Mexico residents were lower than US rates, but followed a similar pattern, increasing slightly from approximately 24 per 100,000 in 1971 to a high of 25 in 1986, and then decreasing gradually to 23 in 1993 (Figure 19).

Spatial Variation

Spatial variation of incidence rates for colon cancer, for the period between 1970 and 1992, among residents of New Mexico, Eddy County, and Lea County, is presented in Tables 18, 19 and 20.

Non-Hispanic Whites: During the period studied, the incidence rate for colon cancer among non-Hispanic white males and females combined was 27.9 per 100,000 statewide, and ranged from a low of 4.4 in Guadalupe County to a high of 42.0 in Rio Arriba County. The incidence rate among non-Hispanic white females was below the corresponding statewide rate in Lea County. For non-Hispanic white males, the incidence rate confidence interval in Eddy County (20 –30.4) was close to non-overlap with the corresponding statewide rate (29.6 – 32).

Hispanic Whites: During the period studied, the incidence rate of colon cancer among Hispanic white males and females combined was 18.3 per 100,000 statewide, and ranged from a low of 6.1 in Sierra County to a high of 38.0 in Catron County.

Temporal Variation

Temporal variation of incidence rates for colon cancer, for the period between 1970 and 1994, among residents of Eddy County and Lea County is presented in Figures 20 and 21.

By Sex: Statewide, colon cancer incidence rates among females have been decreasing since 1986, while rates among males appear to have increased during the period studied. In general, rates among males were higher during the period studied than rates among females. In Eddy County, the colon cancer incidence rates fluctuated widely, but appeared to have increased overall among males, from approximately 25 per 100,000 in 1971 to 30 in 1993, and decreased among females, from approximately 34 per 100,000 in 1971 to 17.5 in 1993. A notable increase in colon cancer incidence among males occurred between 1980 and 1988. In Lea County, the incidence rates fluctuated less widely than in Eddy County during the period studied, and rates among both sexes generally followed the pattern of rates among all New Mexican residents combined. Colon cancer incidence rates among males in Lea County increased from approximately 18 per 100,000 in 1971 to 29 in 1993, and rates among females decreased from approximately 16 per 100,000 in 1971 to 9 in 1993.

By Ethnicity: Statewide, the gap between colon cancer incidence rates among non-Hispanic whites and Hispanic whites during the period studied became smaller, with rates decreasing among non-Hispanic whites, from approximately 30 per 100,000 in 1971 to 24 in 1993, and increasing among Hispanic whites, from approximately 13 per 100,000 in 1971 to 22 in 1993. Still, rates for non-Hispanic whites remained higher than those for Hispanic whites for the entire period studied. In Eddy County, incidence rates for colon cancer were comparable to statewide rates, and in Lea County, incidence rates for colon cancer were slightly lower than statewide rates. In both Eddy and Lea counties, colon cancer incidence for non-Hispanic whites was similar to the rates for all ethnicities combined. Rates for Hispanic whites in both counties fluctuated widely, and in Lea County, no cases of colon cancer among Hispanic whites were reported for several of the years studied.

Laryngeal Cancer

In 1994 in New Mexico, 47 new cases of in situ and invasive cancer of the larynx were reported, accounting for 0.7% of total cancers (NMTR 1996).

Males develop laryngeal cancer more often than women (NCI 1993). Risk factors for cancer of the larynx include use of tobacco (both smoking and chewing) (ACS 1995); heavy alcohol consumption; and exposure to certain substances including asbestos, mustard gas, and nickel or nickel compounds (NCI 1993). The use of tobacco increases the risk of developing laryngeal cancer approximately ten times. The risk associated with tobacco is directly related to the amount of tobacco used, and is compounded by alcohol consumption.

Nationally, incidence rates of cancer of the larynx have not changed overall during the last two decades (NCI 1993). However, rates for men decreased slightly from 8.4 per 100,000 in 1973 to 8.0 in 1990, while rates for women have increased from 1.3 per 100,000 in 1973 to 1.7 in 1990. In New Mexico, incidence rates of laryngeal cancer were lower than US rates, and were fairly stable over the period of study, with rates for men decreasing slightly from approximately 5.7 per 100,000 in 1971 to 5.0 in 1993, and rates for women remaining steady overall (Figure 22).

Spatial Variation

Spatial variation of incidence rates for laryngeal cancer, for the period between 1970 and 1992, among residents of New Mexico, Eddy County, and Lea County, is presented in Tables 21, 22 and 23.

Non-Hispanic Whites: During the period studied, the incidence rate of cancer of the larynx among non-Hispanic white males and females combined was 3.7 per 100,000 statewide, and ranged from a low of no cases in De Baca and Guadalupe counties to a high of 6.9 in Torrance County. The incidence rate of laryngeal cancer among non-Hispanic white males was 8.5 per 100,000 (the sixth highest county rate among non-Hispanic white males in New Mexico). The incidence rate of laryngeal cancer among non-Hispanic white females residing in Lea County was 1.7 per 100,000 (the eighth highest county rate among non-Hispanic white females in New Mexico). Laryngeal cancer incidence rates in Eddy and Lea counties were higher for non-Hispanic white males than non-Hispanic white females: 8.5 vs. 1.5 in Eddy County and 5.6 vs. 1.7 in Lea County.

Hispanic Whites: During the period studied, the incidence rate for cancer of the larynx among Hispanic white males and females combined was 2.6 per 100,000 statewide, and ranged from a low of no cases in Catron, De Baca, Harding, and Union counties to a high of 7.7 in Lea County. Among Hispanic white males residing in Lea County, the incidence rate of laryngeal cancer was 13.9 per 100,000 (the highest county rate among Hispanic white males in New Mexico), and among Hispanic white females residing in Lea County, the incidence rate of laryngeal cancer was 2.3 (the second highest county rate among Hispanic white females in New Mexico). Laryngeal cancer incidence rates for Hispanic white males residing in Eddy and Lea counties were higher than for Hispanic white females: 3.7 vs. 0.00 in Eddy County and 13.9 vs. 2.3 in Lea County.

Temporal Variation

Temporal variation of incidence rates for laryngeal cancer, for the period between 1970 and 1994, among residents of Eddy County and Lea County is presented in Figures 23 and 24.

By Sex: Statewide, incidence rates for cancer of the larynx remained stable during the period studied for both sexes. Laryngeal cancer incidence rates among males were higher than among females during the study period. In Eddy and Lea counties, laryngeal cancer incidence rates were higher among males than among females, and no cases of laryngeal cancer were reported among females for many of the years studied. In Eddy County, the incidence rates for both sexes combined decreased, from approximately 5 per 100,000 in 1971 to 3 in 1993. However, among males, the incidence rates of laryngeal cancer in Eddy County began and ended the period of study at approximately 5.5 or 6.0 per 100,000. In Lea County, laryngeal cancer incidence rates for both sexes combined appeared to increase slightly during the period studied, from approximately 2 per 100,000 in 1971 to 4 in 1993, and rates for males also increased, from approximately 4 per 100,000 in 1971 to 7 in 1993.

By Ethnicity: Statewide, laryngeal cancer incidence rates among both ethnicities did not change substantially during the period studied, and in general, statewide rates were higher among non-Hispanic whites than among Hispanic whites. In Eddy and Lea counties, no cases of laryngeal cancer were reported for Hispanic whites for many of the years studied. In Eddy County, laryngeal cancer incidence rates for non-Hispanic whites decreased during the period studied, from approximately 6 per 100,000 in 1971 to 4 in 1993. In Lea County, laryngeal cancer incidence rates for non-Hispanic whites increased during the period studied, from approximately 1 per 100,000 in 1971 to 4 in 1993.

Leukemia

Leukemia is a group of cancers originating in bone marrow and spreading to the blood, and often to other areas of the body, including the liver, spleen, and lymph nodes (Cotran et al. 1994). In 1994 in New Mexico, 147 cases of newly diagnosed leukemia were reported, accounting for 2.2% of all cancers (NMTR 1996).

Adults are more likely to develop leukemia than children (NCI 1993). However, while leukemia accounts for only about 2.5% of all cancers diagnosed annually in the US, leukemia represents about 30% of all cancers diagnosed in children under 15 years of age. In addition, males in the US are diagnosed with leukemia more often than females. Risk factors for leukemia include genetic disorders such as Down's, Klinefelter's, and Bloom's syndromes; exposure to ionizing radiation; exposure to certain chemicals including benzene; cigarette smoking; and exposure to the adult T-cell leukemia/lymphoma virus. These factors, however, may account for only a small percentage of all leukemia.

Nationally, leukemia incidence rates did not substantially change over the last two decades, except for a slight drop from 10.2 per 100,000 in 1989 to 9 in 1990 (NCI 1993). In New Mexico, leukemia incidence rates were similar to US rates and changed only slightly overall during the period studied, from approximately 9 per 100,000 in 1971 to 9.5 in 1993 (Figure 25).

Spatial Variation

Spatial variation of incidence rates for leukemia, for the period between 1970 and 1992, among residents of New Mexico, Eddy County, and Lea County, is presented in Tables 24, 25 and 26.

Non-Hispanic Whites: During the period studied, the incidence rate for leukemia among non-Hispanic white males and females combined was 11.0 per 100,000 statewide, and ranged from a low of 6.4 in Union County to a high of 20.3 in Harding County. Among non-Hispanic white males in Eddy and Lea counties, leukemia incidence rates were below corresponding statewide rates. The incidence rate of leukemia among non-Hispanic white females in Eddy County was 9.9 per 100,000 (the tenth highest county rate among non-Hispanic white females in New Mexico). The incidence rate of leukemia among non-Hispanic white females in Eddy County was also higher than the incidence rate among non-Hispanic white females in Lea County (5.1 per 100,000).

Hispanic Whites: During the period studied, the incidence rate for leukemia among Hispanic white males and females combined was 7.2 per 100,000 statewide, and ranged from a low of 2.1 in Hidalgo County to a high of 24.8 in Harding County. The leukemia incidence rate among Hispanic white females in Eddy County was 9.3 per 100,000 (the seventh highest county rate among Hispanic white females in New Mexico).

Temporal Variation

Temporal variation of incidence rates of leukemia, for the period between 1970 and 1994, among residents of Eddy County and Lea County is presented in Figures 26 and 27.

By Sex: Statewide, leukemia incidence rates during the period studied increased among males, from approximately 10.5 per 100,000 in 1971 to 12.5 in 1993, and decreased among females, from approximately 8 per 100,000 in 1971 to 7 in 1993. In Lea County, leukemia incidence rates were comparable in magnitude to statewide rates and did not change substantially during the period studied. Incidence rates among both sexes residing in Lea County followed a similar pattern. In Eddy County, incidence rates of leukemia were more variable during the period studied, falling overall for males (during 1973 and 1985) and for females.

By Ethnicity: Statewide, leukemia incidence rates during the period studied increased slightly among Hispanic whites, from approximately 6 per 100,000 in 1971 to 8 in 1993, but decreased slightly among non-Hispanic whites, from approximately 11 per 100,000 in 1971 to 10 in 1993. Leukemia incidence rates among non-Hispanic whites were higher than those among Hispanic whites during the study period, and appear to determine the magnitude and fluctuation of county-level rates for all ethnicities combined. In Eddy County, leukemia incidence rates for non-Hispanic whites decreased over the period studied from approximately 17 per 100,000 in 1971 to 10 in 1993. Rates for Hispanic whites were more variable, with peaks around 1977 and 1984, and no cases of leukemia reported for several of the years studied. In Lea County, leukemia incidence rates for non-Hispanic whites began and ended the study period at approximately 10 per 100,000, but varied slightly for intervening years. Rates for Hispanic whites in Lea County were more variable, with a peak in 1973 and no cases of leukemia reported for several of the years studied.

Liver Cancer

The liver is a principal site for metastasis of cancer from other anatomical sites. However, in 1994 in New Mexico, just 50 cases of primary in situ and invasive liver cancer were reported, accounting for 0.8% of total cancers (NMTR 1996).

Although rare in the US, liver cancer incidence is high in countries bordering the Mediterranean Sea, and a leading cause of death in Taiwan, Mozambique, and Southeast China (Crawford 1994). In countries with high liver cancer incidence, males are diagnosed with this cancer about eight times more frequently than females. In countries such as the US, where liver cancer incidence is relatively low, males are diagnosed with this cancer about two or three times more frequently than females. Risk factors for liver cancer include chronic hepatitis B and C virus infection, exposure to aflatoxin (a substance secreted by a mold found on peanuts and other foods), exposure to thorotrast (a radioactive material used in medical radiological procedures until the 1950s), exposure to ionizing radiation, consumption of alcohol, use of anabolic steroids, long-term use of oral contraceptives, and tyrosinemia (a genetic metabolic disorder) (NCI 1993; Crawford 1994; Mettler 1995). In the US, the major risk factors for liver cancer are cirrhosis of the liver due to alcohol consumption, and chronic hepatitis B or C infections (which account for as much as half the cases of liver cancer) (NCI 1993).

Nationally, invasive liver cancer incidence rates have increased slightly over the last two decades, from 2.3 per 100,000 in 1973 to 3.1 in 1990 (NCI 1993). In New Mexico, incidence rates of liver cancer did not substantially change from the beginning to the end of the period studied, but varied slightly, ranging from a low of approximately 2 per 100,000 in 1984 to a high of 2.7 in 1993 (Figure 28). Incidence rates of liver cancer in New Mexico were comparable to US rates (NCI 1993).

Spatial Variation

Spatial variation of incidence rates for liver cancer, for the period between 1970 and 1992, among residents of New Mexico, Eddy County, and Lea County, is presented in Tables 27, 28 and 29.

Non-Hispanic Whites: During the period studied, the incidence rate for liver cancer among non-Hispanic white males and females combined was 1.8 per 100,000 statewide, and ranged from a low of no cases in De Baca, Guadalupe, and Mora counties to a high of 5.1 in Catron County. The incidence rate of liver cancer among non-Hispanic white females in Lea County was 1.9 per 100,000 (the eighth highest county rate among non-Hispanic white females in New Mexico).

Hispanic Whites: During the period studied, the incidence rate of liver cancer among Hispanic white males and females combined was 3.3 per 100,000 statewide, and ranged from a low of no cases in Catron, De Baca, Harding, Mora, and Roosevelt counties to a high of 6.5 in Lea County. The liver cancer incidence rate among Hispanic white males in Eddy County was 8.3 per 100,000 (the fourth highest county rate among Hispanic white males in New Mexico). The liver cancer incidence rate among Hispanic white males was higher than among females in Eddy County (8.3 vs. 0.8).

Temporal Variation

Temporal variation of incidence rates of liver cancer, for the period between 1970 and 1994, among residents of Eddy County and Lea County is presented in Figures 29 and 30.

By Sex: Statewide, liver cancer incidence rates showed little variation over the period studied, ranging from a low of approximately 2.7 per 100,000 around 1975 to a high of 4.3 in 1992 among males, and ranging from a high of approximately 2.1 per 100,000 in 1974 to a low of 1.0 in 1984 among females. In Eddy County, liver cancer incidence rates decreased for both sexes combined, from approximately 2.5 per 100,000 in 1971 to 0.5 in 1993, and for males, from approximately 4 per 100,000 in 1971 to 1 in 1993. Liver cancer incidence rates among females residing in Eddy County were variable, with no incidence of liver cancer reported for many of the years studied. In Lea County, incidence rates for both sexes combined were variable, ranging from a low of approximately 0.5 per 100,000 in 1977 to a high of 4.5 in 1990, but began and ended the study period at approximately 1 or 2 per 100,000. No cases of liver cancer were reported in Lea County for many of the years studied.

By Ethnicity: Statewide, liver cancer incidence rates decreased during the period studied for non-Hispanic whites, from approximately 2.5 per 100,000 in 1971 to 1.8 in 1993, and increased for Hispanic whites, from approximately 3.0 per 100,000 in 1971 to 4.4 in 1993. In general, liver cancer incidence rates for Hispanic whites were higher than rates for non-Hispanic whites. Rates for Hispanic whites in both counties were variable, with no incidence of liver cancer reported for many of the years studied. In Eddy County, liver cancer incidence rates of non-Hispanic whites decreased from approximately 2.0 per 100,000 in 1971 to about 0.7 in 1993. In Lea County, liver cancer incidence rates of non-Hispanic whites did not substantially change from the beginning to the end of the period studied, ranging from a low of no cases between 1973 and 1978, to a high of approximately 5.5 per 100,000 in 1980.

Lung Cancer

Nationally, lung cancer is the second most frequently diagnosed cancer in both sexes (NCI 1993). In 1993 in New Mexico, lung cancer was also the second most frequently diagnosed cancer in both sexes, and the leading cause of death from cancer for Hispanic white males and non-Hispanic whites (Figures 1, 2 and 3).

Smoking may be responsible for 90% of lung cancers diagnosed in men and 87% in women in the US (ACS 1995). Thus, lung cancer incidence rates are closely related to smoking patterns, and the vast majority of lung cancer cases and deaths are preventable. Other risk factors include exposure to environmental tobacco smoke; exposure to ionizing radiation from sources such as radon (a naturally occurring gas formed by the radioactive decay of radium and uranium) or medical procedures; and exposure to certain substances and chemicals such as asbestos, arsenic, mustard gas, hexavalent chromium compounds, nickel compounds, and polycyclic aromatic hydrocarbons (Sax 1987; NCI 1993). Men who smoke two packs of cigarettes per day have 22 times the risk of dying from lung cancer than non-smokers (CCDPHP 1990), and women who smoke have 12 times the risk of dying from lung cancer than non-smokers (NCI 1993). In addition, exposure of cigarette smokers to substances such as radon and arsenic increases the risk of developing lung cancer (Kobzik and Schoen 1994; ACS 1995) and asbestos workers who smoke have a 50 to 90 times greater risk of developing lung cancer than those who do not smoke (Kobzik and Schoen 1994).

Nationally, lung cancer incidence rates have increased over the last two decades, from 42.5 per 100,000 in 1973 to 57.3 in 1990. However, while experiencing an overall increase, incidence rates appear to have started leveling off or declining in 1988 (NCI 1995) as a result of declining smoking rates among males. Lung cancer incidence rates among US females have more than doubled in the last two decades, increasing from 18.2 per 100,000 in 1973 to 40.7 in 1990. In New Mexico, incidence rates of lung cancer over the period studied followed the same pattern as, but were lower than, lung cancer incidence rates for the US. Statewide rates increased overall, from approximately 35 per 100,000 in 1971 to 38 in 1993, but began to level off in the late 1980s. Statewide rates among males appear to have slowly decreased, from approximately 57 per 100,000 in 1971 to 51 in 1993. Statewide rates among females have almost doubled, increasing from approximately 15 per 100,000 in 1971 to 28 in 1993 (Figure 31).

Spatial Variation

Spatial variation of incidence rates for lung cancer, for the period between 1970 and 1992, among residents of New Mexico, Eddy County, and Lea County, is presented in Tables 30, 31 and 32.

Non-Hispanic Whites: During the period studied, the incidence rate for lung cancer among non-Hispanic white males and females combined was 47.7 per 100,000 statewide, and ranged from a low of 23.1 in Harding County to a high of 65.2 in Valencia/Cibola counties. Among non-Hispanic white males, the lung cancer incidence rate in Eddy County was above the corresponding statewide rate: 88.0 per 100,000 (the fifth highest county rate among non-Hispanic white males in New Mexico) vs. 71.2 statewide. The lung cancer incidence rate among non-Hispanic white females in Eddy County was 34.2 per 100,000 (the fifth highest county rate among non-Hispanic white females in New Mexico), which was higher than in Lea County. Lung cancer incidence rates for non-Hispanic white males residing in Eddy and Lea counties were more than two times higher than for non-Hispanic white females: 88.0 vs. 34.2 in Eddy County and 73.4 vs. 25.4 in Lea County.

Hispanic Whites: During the period studied, the incidence rate for lung cancer among Hispanic white males and females combined was 23.6 per 100,000 statewide, and ranged from a low of no cases in Harding County to a high of 31.8 in Luna and Union counties. The lung cancer incidence rate among Hispanic white females in Eddy County was 19.2 per 100,000 (the eighth highest county rate among Hispanic white females in New Mexico).

Temporal Variation

Temporal variation of incidence rates for lung cancer, for the period between 1970 and 1994, among residents of Eddy County and Lea County is presented in Figures 32 and 33.

By Sex: In Eddy and Lea counties, lung cancer incidence rates were higher among males than females for the period studied, and neither sex independently determined the magnitude and fluctuation of rates for both sexes combined. In Eddy County, lung cancer incidence rates for both sexes combined followed the same overall patterns as the statewide rates, increasing slightly from approximately 50 per 100,000 in 1971 to 53 in 1993, but varied more widely. Among males residing in Eddy County, incidence rates of lung cancer during the period studied decreased slightly, from approximately 77 per 100,000 in 1971 to 60 in 1993, and among females residing in Eddy County, rates increased from approximately 25 per 100,000 in 1971 to 43 in 1993. Lung cancer incidence rates among males in Eddy County fluctuated more than rates among females during the period studied, with a peak in rates beginning around 1973 and ending around 1981. In Lea County, lung cancer incidence rates among males decreased from approximately 85 per 100,000 in 1971 to 55 in 1993, and rates among females increased from approximately 12 per 100,000 in 1971 to 20 in 1993. Rates for both sexes combined decreased, from approximately 50 per 100,000 in 1971 to 37 in 1993. As in Eddy County, rates among males in Lea County fluctuated more widely than among females, with a peak of approximately 95 per 100,000 in 1972 and a low of 35 in 1987.

By Ethnicity: Statewide, incidence rates of lung cancer increased over the period studied among Hispanic whites, from approximately 20 per 100,000 in 1971 to 27 in 1993, and among non-Hispanic whites increased, from approximately 44 per 100,000 in 1971 to a peak of 50 during the late 1980s. In Eddy and Lea counties, lung cancer incidence rates were higher during the period studied among non-Hispanic whites than among Hispanic whites. In Eddy County, lung cancer incidence rates for non-Hispanic whites did not substantially change from the beginning to the end of the study period, but varied for intervening years, ranging from a low of approximately 40 per 100,000 in 1973 to a high of 75 in 1988. Incidence rates among Hispanic whites in Eddy County increased, from approximately 18 per 100,000 in 1971 to 35 in 1993. In Lea County, lung cancer incidence rates among non-Hispanic whites decreased over the period studied, from approximately 49 per 100,000 in 1971 to 40 in 1993. No cases of lung cancer among Hispanic whites were reported until 1979 in Lea County, and after 1979, rates varied widely, ranging from a low of approximately 10 per 100,000 in 1982 and 1993, to a high of 45 in 1990.

Non-Hodgkin's Lymphoma

Lymphomas are a group of cancers of the lymphatic system (NCI 1993). Hodgkin's lymphomas are separated from this group, and all other lymphomas are termed non-Hodgkin's lymphomas. In 1993 in New Mexico, lymphomas (both Hodgkin's and non-Hodgkin's) were the fifth most commonly diagnosed cancer among all men combined and among Hispanic white men (Figures 1 and 3). In 1994 in New Mexico, 216 new cases of non-Hodgkin's lymphomas were diagnosed, accounting for 3.3% of all cancers (NMTR 1996).

In general, males are diagnosed with non-Hodgkin's lymphomas more often than females; however, males and females over 65 years of age are diagnosed at the same rate (NCI 1993). Risk factors are not well known, but may include viruses such as HIV, human T-cell leukemia virus-1, and Epstein-Barr virus; health conditions such as asthma, allergies, arthritis, rheumatic fever, tuberculosis, and infectious mononucleosis; drugs such as certain agents used for chemotherapy and common steroids; and certain chemicals including pesticides.

Nationally, the incidence rates of non-Hodgkin's lymphomas increased by about 150% over the last two decades, from 8.5 per 100,000 in 1973 to 14.9 in 1990 (NCI 1993). Rates among males increased more than among females (males by 83% and females by about 61%). The incidence rates of non-Hodgkin's lymphomas were substantially higher among males between 20 and 54 years old residing in the San Francisco/Oakland area. However, even if this group is not included, the incidence of non-Hodgkin's lymphomas increased among men in this age group. HIV accounts for only part of the increase in incidence rates of non-Hodgkin's lymphomas, although it may account for more of these increases in the future. Other risk factors probably account for less than 50% of the incidence rate increases of the last four decades. In New Mexico, incidence rates of non-Hodgkin's lymphomas increased over the period of study, from approximately 6 per 100,000 in 1971 to 11 in 1993 (Figure 34), but are generally lower than US rates.

Spatial Variation

Spatial variation of incidence rates for non-Hodgkin's lymphomas, for the period between 1970 and 1992, among residents of New Mexico, Eddy County, and Lea County, is presented in Tables 33, 34 and 35.

Non-Hispanic Whites: During the period studied, the incidence rate for non-Hodgkin's lymphoma among non-Hispanic white males and females combined was 10.6 per 100,000 statewide, and ranged from a low of 3.6 in Guadalupe County to a high of 18.1 in Taos County. The incidence rate among non-Hispanic white females in Lea County was below the corresponding statewide rate.

Hispanic Whites: During the period studied, the incidence rate for non-Hodgkin's lymphoma among Hispanic white males and females combined was 6.7 per 100,000 statewide, and ranged from a low of no cases in Catron, De Baca, and Los Alamos counties to a high of 11.6 in Eddy County. Incidence rates of non-Hodgkin's lymphoma among Hispanic white males in Eddy County were above the corresponding statewide rates. The incidence rate for Hispanic white males in Eddy county was 15.7 per 100,000 (the highest county rate among Hispanic white males in New Mexico), and for Hispanic white females in Eddy County was 7.8 per 100,000 (the fourth highest county rate among Hispanic white females in New Mexico). These incidence rates of non-Hodgkin’s lymphoma among Hispanic white males and Hispanic white females in Eddy County were higher than the corresponding rates in Lea County. The incidence rate for non-Hodgkin’s lymphoma among Hispanic white females in Lea County was below the corresponding statewide rates, and the incidence rate among Hispanic white males in Lea County (2.7) was higher than among Hispanic white females (no cases).

Temporal Variation

Temporal variation of incidence rates for non-Hodgkin's lymphomas, for the period between 1970 and 1994, among residents of Eddy County and Lea County is presented in Figures 35 and 36.

By Sex: Statewide, incidence rates of non-Hodgkin's lymphomas increased among both sexes over the period studied. Incidence rates among males were higher than among females, and increased from approximately 8 per 100,000 in 1971 to 13 in 1993. Rates among females residing in New Mexico increased from approximately 5 per 100,000 in 1971 to 10 in 1993. In Eddy County, incidence rates of non-Hodgkin's lymphoma increased overall during the study period for both sexes combined, from approximately 9 per 100,000 in 1971 to 15 in 1993. Rates also increased among males, from 7 in 1971 to 19 in 1993, and among females, from 10 in 1971 to 13 in 1993. Rates among males dropped below rates among females for several years around 1974 and experienced peaks beginning in the early 1970s and early 1980s. In Lea County, incidence rates for non-Hodgkin's lymphoma decreased overall during the study period for both sexes combined, from approximately 8 per 100,000 in 1971 to under 4 in 1993. Rates also increased among males, from approximately 12.5 per 100,000 in 1971 to under 4 in 1993. Rates for females began and ended the study period at approximately 4 per 100,000, but ranged for the intervening years from a low of no cases between 1987 and 1989 to a high of approximately 14 per 100,000 in 1985. Incidence rates for non-Hodgkin's lymphoma showed several notable peaks, for males, around 1973 and 1981, and for females, around 1976 and 1985.

By Ethnicity: Statewide, incidence rates for non-Hodgkin's lymphoma among non-Hispanic whites and Hispanic whites increased steadily during the period studied. Incidence rates for non-Hispanic whites increased from approximately 7.5 per 100,000 in 1971 to 13 in 1993, and for Hispanic whites increased from approximately 4 per 100,000 in 1971 to 9 in 1993. In general, incidence rates for non-Hodgkin's lymphoma during the period studied were higher among non-Hispanic whites than among Hispanic whites. In Eddy County, incidence rates for non-Hodgkin's lymphoma increased among non-Hispanic whites during the period studied from approximately 9 per 100,000 in 1971 to 15 in 1993, and among Hispanic whites, from approximately 5 per 100,000 in 1975 to 23 in 1993. In Lea County, the incidence rates among non-Hispanic whites decreased during the period studied, from approximately 8 per 100,000 in 1971 to under 5 in 1993. No Hispanic whites were diagnosed with non-Hodgkin's lymphoma in Lea County for many of the years studied.

Ovarian Cancer

Ovarian cancer is responsible for 6% of cancers in women (Crum 1994). Because ovarian cancers are not easily detected in early stages, they result in a disproportionate number of deaths. In 1993 in New Mexico, cancer of the ovary was the fifth most frequently diagnosed cancer among females, and the fourth most frequently diagnosed cancer among non-Hispanic white females (Figures 1 and 3).

During the period between 1986 and 1990, US women aged 65 years and over were diagnosed with this cancer almost six times more than women under 65 years (NCI 1993). Risk factors are not well understood for this cancer. Being infertile and having a family history of ovarian cancer have both been demonstrated to increase the risk of developing ovarian cancer. Other risk factors may involve diet and metabolism

Nationally, invasive ovarian cancer incidence rates have remained about the same over the last two decades, starting at 14.1 per 100,000 in 1973 and ending at 14.9 in 1990 (NCI 1993). While there was a slight peak from 1988 to 1990 (reaching 15.1 per 100,000 in 1989), the average incidence rate for the period between 1989 and 1990 (14.3 per 100,000), is consistent with other values between 1973 and 1990. Females 50 years old and over were diagnosed with this cancer about ten times more than women under 50 between 1973 and 1990. In New Mexico, incidence rates of invasive ovarian cancer were slightly lower than US rates. Statewide rates did not substantially change overall from 1970 to 1992, although they varied for intervening years, ranging from a low of approximately 12 per 100,000 around 1980, to a high of 15 in 1992 (Figure 37).

Spatial Variation

Spatial variation of incidence rates for ovarian cancer, for the period between 1970 and 1992, among females residing in New Mexico, Eddy County, and Lea County, is presented in Table 36.

Non-Hispanic Whi