TUBAL-STERILIZATION AND THE RISK OF ENDOMETRIAL CANCER

Several animal and human studies suggest that tubal occlusion may curt ail ovarian function, altering the production and balance of endogenou s estrogens and progesterone, 2 hormones closely related to endometria l carcinogenesis. Despite this, and the increasing world-wide populari ty of this method of contraception, little is known about its relation ship with the risk of developing endometrial cancer. To assess whether tubal sterilization influences a woman's risk of developing epithelia l endometrial carcinoma, data from a large multicenter population-base d case-control study of endometrial cancer were analyzed. Cases were 4 37 women aged 20 to 54 years with histologically confirmed epithelial endometrial cancer ascertained through 6 population-based cancer regis tries in the United States. Controls were 3200 women selected at rando m from the populations of the areas from which the cases were detected . As compared with women who had never had tubal sterilization, women who had had this surgery had a crude odds ratio of 0.58 [95% confidenc e interval (CI), 0.43-0.78]. However, after adjusting for the combined confounding effects of age and parity, the magnitude of the protectiv e association decreased to 0.87 (95% CI, 0.63-1.20). The magnitude of the protective effect did not significantly change with years since su rgery or age at surgery. Although a modest, non-significant protective effect is suggested, these findings indicate that tubal sterilization does not substantially alter the risk of developing epithelial endome trial cancer in women 20 to 54 years of age. If there is an increase i n risk, these data indicate that it is unlikely to be any greater than 20%. (C) 1996 Wiley-Liss, Inc.