Trends in the incidence of cancer of the corpus uteri in Connecticut, 1964-1979, in relation to consumption of exogenous estrogens.

The incidence of cancer of the uterine corpus diagnosed in the localized 1964 and 1969. During the next six years, however, it increased substantially, reaching a peak in 1975, followed by an irregular decline through 1979. Women aged 45-64 years showed both the largest increase and the sharpest decline. The incidence of tumors diagnosed with regional or distant spread has been rising slightly but consistently through the period 1970-1979; this upward trend is statistically significant (p less than 0.01). Rates corrected for hysterectomized women not truly at risk are 40-50% higher than uncorrected rates but trends are the same. Explanations which are considered are changes in diagnostic practices and changes in risk factor prevalence. The use of noncontraceptive oral estrogens, a well documented risk factor for endometrial cancer, increased between 1964 and 1975 and then declined sharply through 1979 in the United States. The importance of these compounds in explaining the observed incidence trends is considered in terms of the major time- and stage-specific features of the exogenous estrogen-endometrial cancer association reported in the case-control studies.