Cancer Incidence Rates in Eddy and Lea Counties

New Mexico, 1970-1994

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.