Tubal sterilization and the risk of endometrial cancer

Several animal and human studies suggest that tubal occlusion may curtail ovarian function, altering the production and balance of endogenous estrogens and progesterone, 2 hormones closely related to endometrial carcinogenesis. Despite this, and the increasing world-wide popularity of this method of contraception, little is known about its relationship with the risk of developing endometrial cancer. To assess whether tubal sterilization influences a woman's risk of developing epithelial endometrial carcinoma, data from a large multicenter population-based case-control study of endometrial cancer were analyzed. Cases were 437 women aged 20 to 54 years with histologically confirmed epithelial endometrial cancer ascertained through 6 population-based cancer registries in the United States. Controls were 3200 women selected at random 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% confidence interval (CI), 0.43-0.78]. However, after adjusting for the combined confounding effects of age and parity, the magnitude of the protective association decreased to 0.87 (95% CI, 0.63-1.20). The magnitude of the protective effect did not significantly change with years since surgery 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 endometrial cancer in women 20 to 54 years of age. If there is an increase in risk, these data indicate that it is unlikely to be any greater than 20%.