TUBAL-STERILIZATION, HYSTERECTOMY, AND THE SUBSEQUENT OCCURRENCE OF EPITHELIAL OVARIAN-CANCER

Several hypotheses predict that tubal sterilization and hysterectomy may influence a woman's risk of developing ovarian cancer. To examine the relation between these surgeries and epithelial ovarian cancer, the authors analyzed data from the Cancer and Steroid Hormone Study, a case-control study of women aged 20-54 years. Eight population-based cancer registries in the United States identified women with newly diagnosed epithelial ovarian cancer during 1980-1982 (n = 494). A comparison sample of female residents of these eight areas (n = 4,238) was identified through random digit dialing. Women who had had tubal sterilization (relative risk (RR) = 0.69, 95% confidence interval (CI) 0.50-0.95), a hysterectomy only (RR = 0.55, 95% CI 0.38-0.81), or a hysterectomy with unilateral oophorectomy (RR = 0.60, 95% CI 0.31-1.17) had lower risks of ovarian cancer than did women who had never had any sterilization surgery. However, the negative associations with tubal sterilization and hysterectomy only appeared to wane after two decades. These findings may be partly explained by the screening for occult ovarian pathology that often accompanies pelvic surgery: Women whose ovaries screen as "negative" may be temporarily at low risk of being diagnosed with ovarian cancer. However, because the decreased risks persisted for so long, it is conceivable that hormonal, mechanical, or circulatory sequelae of these sterilization procedures may act to lower ovarian cancer risk.