TUBAL-LIGATION AND FATAL OVARIAN-CANCER IN A LARGE PROSPECTIVE COHORTSTUDY

Several studies suggest that tubal sterilization may decrease the risk of ovarian cancer. Data from the Cancer Prevention Study II were anal yzed to examine the relation between tubal ligation and ovarian cancer mortality in a targe prospective study. A total of 396,114 women who had not had hysterectomies and who had no prior history of cancer (exc ept nonmelanoma skin cancer) were followed prospectively for approxima tely 9 years from 1982 to 1991. During this time, 799 ovarian cancer d eaths were observed. Tubal ligation was significantly associated with a decreased risk of ovarian cancer mortality in an age- and race-adjus ted Cox proportional hazards model (hazard ratio (HR) = 0.64, 95% conf idence interval (Cl) 0.42-0.96), and the results were essentially unch anged when controlling for potential ovarian cancer risk factors (HR = 0.68, 95% CI 0.45-1.03). The protective effect appeared to be greater in the first 20 years after the procedure (HR = 0.49, 95% CI 0.24-0.9 9) than later (HR = 0.80, 95% CI 0.48-1.34). No interactions between e ver having had a tubal ligation and other covariates were observed. Th ese data suggest that tubal ligation reduces the risk of fatal ovarian cancer.