Cancer Incidence Rates in Eddy and Lea Counties

New Mexico, 1970-1994

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.