Background: In the general population, the risk of developing ovarian cancer is reduced in women who have undergone tubal ligation, hysterectomy, or oophorectomy, although peritoneal cancer can arise after bilateral oophorectomy. In studies from genetic screening clinics, women with mutations in the breast and ovarian susceptibility genes BRCA1 and BRCA2 have been found to have a low risk of peritoneal carcinoma in the first years after bilateral oophorectomy. We assessed the level and persistence of reduction of ovarian (including peritoneal) cancer risk after gynecologic surgeries for women who carry BRCA1/2 mutations but were not selected from high-risk clinics.
Methods: We identified 1124 Israeli women with incident ovarian cancer or primary peritoneal cancer and tested 847 of them for the three Ashkenazi founder mutations. We compared gynecologic surgery history among all case patients, BRCA1 (n = 187) and BRCA2 (n = 64) carrier case patients, and the non-carrier case patients (n = 598) with that in control subjects drawn from a population registry (n = 2396). We estimated ovarian cancer risk (odds ratios [ORs] with 95% confidence intervals [CIs]) after gynecologic surgery in mutation carriers and non-carriers with logistic regression models.
Results: Eight women with primary peritoneal cancer and 128 control subjects reported a previous bilateral oophorectomy (OR = 0.12, 95% CI = 0.06 to 0.24). Other gynecologic surgeries were associated with a 30%-50% reduced risk of ovarian cancer, depending on the type of surgery, with surgery to remove some ovarian tissue associated with the most risk reduction (OR = 0.34, 95% CI = 0.16 to 0.74). Reduced risks were seen in BRCA1/2 carriers and non-carriers. Age at surgery and years since surgery did not affect risk reductions.
Conclusion: Both BRCA1/2 mutation carriers and non-carriers have reduced risk of ovarian or peritoneal cancer after gynecologic surgery. The magnitude of the reduction depends upon the type and extent of surgery.