Hysterectomy with or without unilateral oophorectomy and risk of ovarian cancer

This study was conducted to investigate the incidence of ovarian cancer in women who had undergone previous hysterectomy with or without unilateral oophorectomy. In 4 different regions of Italy, from January 1992 to September 1999, 1031 patients with primary invasive epithelial ovarian cancer were interviewed for information about personal health and clinical characteristics, including family history of cancer, use of oral contraceptives or hormone replacement therapy, and clinical history, especially hysterectomy with or without oophorectomy. Also interviewed were 2411 control patients who were recruited from women admitted to the same network of hospitals who were near the same ages as study patients (median, 57 years; range, 17-79 years). Control patients were being treated for indications other than cancer, hormonal, or gynecologic conditions and had no known risk factors for ovarian cancer. All interviews were conducted while patients were in the hospital. Surgical information was confirmed in the medical records. Among all 64 (6.2%) study patients and 248 (10.3%) controls who had previous pelvic surgery, including hysterectomy (n = 40, 3.9%) unilateral oophorectomy (n = 10, 1%), or hysterectomy with unilateral oophorectomy (n = 14, 1.4%), the risk of developing ovarian cancer was less than the risk for women with no previous pelvic surgery (odds ratio [OR], 0.6; 95% confidence interval [CI], 0.5-0.9). The risk decreased as the length of time since surgery increased. For women 1 to 7 years from surgery, the OR was 0.8 (95% CI, 0.5-1.4), and for those 15 or more years from surgery, the OR was 0.5 (95% CI, 1.3-0.8) (P = .005). Age at the time of surgery did not affect the results. The risk of developing ovarian cancer after pelvic surgery was greater among women under 60 years of age than among those 60 years old or more (OR, 0.9; 95% CI, 0.6-1.3 vs. OR, 0.4; 95% CI, 0.2-0.6). Neither family history of breast or ovarian cancer nor parity affected the outcome of the analysis.