Breast cancer risk after hysterectomy with and without salpingo-oophorectomy for benign indications.

BACKGROUND: Breast cancer risk has been extensively studied in women with genetic predisposition, that is, mutations in breast cancer genes 1 and 2. Although there are guidelines for performing bilateral salpingo-oophorectomies in individuals with specific genetic risks, oophorectomies are also performed in many women considered to be at average risk of developing breast cancer. The risk of breast cancer in women with average risk who undergo hysterectomy with bilateral salpingo-oophorectomy for benign indications is less clear. OBJECTIVE: This study aimed to estimate breast cancer risk after hysterectomy with and without concomitant bilateral salpingo-oophorectomy for benign indications. STUDY DESIGN: From 2001 to 2015, women aged 18 years and older from Kaiser Permanente Northern California who underwent hysterectomy alone and hysterectomy with bilateral salpingo-oophorectomy were identified using the International Classification of Diseases, Ninth Revision, procedure and Current Procedural Terminology codes. Women with a breast cancer gene mutation and previous history of breast cancer or gynecologic cancer were excluded. Descriptive and bivariate analyses were used to describe and compare demographic and clinical characteristics. Breast cancer incidence rates were calculated per 100,000 person-years. Survival analysis and Cox proportional hazard models were conducted to compare the risk of developing breast cancer. RESULTS: Of 49,215 women who underwent hysterectomy, 19,826 had hysterectomy with bilateral salpingo-oophorectomy. Whites, Hispanics, blacks, Asians, and other or unknown comprised 51.2%, 20.3%, 12.7%, 10.4%, and 5.3% of the study population, respectively. The average age of women with hysterectomy alone was 45.5 years compared with 50.8 years for those who had hysterectomy with bilateral salpingo-oophorectomy. During the study period, 915 women received a diagnosis of breast cancer. Age-specific breast cancer incidence rates were higher in women older than 60 years with oophorectomy than hysterectomy alone (471.2 [95% confidence interval, 386.2-556.2] vs 463.0 [95% confidence interval, 349.6-576.5], respectively). After controlling for age, race, income, and Charlson Comorbidity Index, women with bilateral salpingo-oophorectomy had a 14% lower risk of breast cancer than women with hysterectomy alone (hazard ratio, 0.86; 95% confidence interval, 0.75-0.98). All-cause mortality was higher with oophorectomy than hysterectomy alone (64.4% vs 35.6%, P<.0001, respectively). CONCLUSION: Women with concurrent bilateral salpingo-oophorectomy for benign indications had a lower risk of breast cancer than those who had hysterectomy alone. However, all-cause mortality was higher in women with oophorectomy. Perimenopausal patients undergoing hysterectomy for benign indications should be counseled on the risks and benefits of oophorectomy at the time of surgery.