Cancer Incidence Rates in Eddy and Lea Counties

New Mexico, 1970-1994

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.