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.