Time trend and age-period-cohort effect on incidence of bladder cancer in Connecticut, 1935-1992.

Earlier studies indicated that the incidence rates for bladder cancers rose rapidly in both the United States and Europe. Tobacco smoking is considered to be the major risk factor for urinary bladder cancer, and recent studies from Connecticut show that several smoking-related cancers have started leveling off or decreasing. The time trend for bladder cancer, however, is not clear in Connecticut. The current study examined the long-term trend of bladder cancer in Connecticut. Our results show that urinary bladder cancer has been increasing, with a marked increase among males. The rate of increase, however, has slowed since the early 1980s. Birth-cohort examination shows that the rates have leveled off for those born after about 1935 in both males and females. Age-period-cohort modeling results also show that the birth-cohort patterns of bladder cancer are somewhat similar to those observed for lung cancer in Connecticut, thus supporting the findings from analytical epidemiologic studies which indicate that cigarette smoking is one of the major risk factors for urinary bladder cancer. Our results also suggest that the difference in environmental and occupational exposures between males and females may be responsible for the large difference in the incidence rate of bladder cancer seen between the sexes.