Cancer Incidence Rates in Eddy and Lea Counties

New Mexico, 1970-1994

Childhood Cancer-Leukemia

Leukemia accounts for more than 30% of all childhood cancers (NCI 1993) and causes more deaths in children 14 years old and under than all other childhood cancers combined (Schofield and Cotran 1994).

Risk factors for childhood leukemia have not been clearly identified, but may include exposure to ionizing radiation, and theoretically, exposure to certain chemicals such as benzene, although no cases have been reported (NCI 1993).

Nationally, childhood leukemia cancer incidence rates fluctuated slightly during the period between 1973 and 1990, with a low of 3.1 per 100,000 in 1975 and a high of 4.8 in 1974 (NCI 1993). In New Mexico, incidence rates of childhood leukemia were comparable to US rates and varied widely over the study period, with a low of approximately 28 per 1,000,000 (2.8 per 100,000) in 1978, and a high of 55 (5.5 per 100,000) in 1991 (Figure 55).

Spatial Variation

Spatial variation of incidence rates for childhood leukemia, for the period between 1970 and 1992, among residents under 15 years old in New Mexico, Eddy County, and Lea County, is presented in Tables 48, 49 and 50. Incidence rates for childhood cancer are expressed in rate per 1,000,000 people per year.

Non-Hispanic Whites: During the period studied, the incidence rate for childhood leukemia among non-Hispanic white males and females combined was 41 per 1,000,000 statewide, and ranged from a low of no cases in De Baca, Guadalupe, Harding, Hidalgo, Mora, San Miguel, Torrance, and Union counties to a high of 124 in Catron County. The incidence rate of childhood leukemia among non-Hispanic white females in Eddy County was 65.2 per 1,000,000 (the sixth highest county rate among non-Hispanic white females in New Mexico).

Hispanic Whites: During the period studied, the incidence rate for childhood leukemia among Hispanic white males and females combined was 40.3 per 1,000,000 statewide, and ranged from a low of no cases in Catron, De Baca, Hidalgo, Mora, Roosevelt, Sierra, Socorro, and Torrance counties to a high of 362 in Harding County. The childhood leukemia incidence rate among Hispanic white males in Lea County was 45.5 per 1,000,000 (the tenth highest county rate among Hispanic white males in New Mexico). Among Hispanic white females, the childhood leukemia incidence rate in Eddy County was 62.5 per 1,000,000 (the seventh highest county rate among Hispanic white females in New Mexico) and in Lea County was 50.2 per 1,000,000 (the eighth highest county rate among Hispanic white females in New Mexico).

Temporal Variation

Temporal variation of incidence rates for childhood leukemia, for the period between 1970 and 1994, among residents under 15 years old in Eddy County and Lea County is presented in Figures 56 and 57. Incidence rates for childhood cancer are expressed in rate per 1,000,000 people per year.

By Sex: Statewide, incidence rates for childhood leukemia during the period studied showed no substantial increasing or decreasing trends among either sex. In general, rates for males were slightly higher than for females. In Eddy County, incidence rates for childhood leukemia varied during the study period, with no cases reported for many of the years studied and a peak in incidence rates among females from 1981 to 1988. Incidence rates also varied in Lea County during the study period, ranging from a low of approximately 20 per 1,000,000 in 1970 to 1972, 1981 to 1983, and 1989 to 1991, to a high of 80 in 1977. No cases of childhood leukemia in Lea County were reported for several of the years during the study period.

By Ethnicity: Statewide, incidence rates of childhood leukemia among non-Hispanic whites decreased slightly and rates among Hispanic whites increased. In Eddy County, incidence rates of childhood leukemia varied widely for non-Hispanic whites and Hispanic whites, with no cases reported for several of the years studied among both groups, and a peak in rates of approximately 120 per 1,000,000 among Hispanic whites in 1978. In Lea County, incidence rates of childhood leukemia also varied for both ethnicities, with no cases reported for several of the years studied.