Prognosis of women with stage I endometrioid endometrial cancer and synchronous stage I endometrioid ovarian cancer

Objective Synchronous endometrial and ovarian cancer with endometrioid histology at two cancer sites typically presents with early-stage disease and is thought to have a good prognosis. We examined the survival of women with early-stage endometrioid endometrial cancer who had synchronous early-stage endometrioid ovarian cancer. Methods This is a retrospective case-control study examining the Surveillance, Epidemiology, and End Result Program between 1973 and 2013. Survival of women with stage I endometrioid endometrial cancer with stage I endometrioid ovarian cancer (n = 839) were compared to women with stage I endometrioid endometrial cancer without synchronous ovarian cancer (n = 123,692) after propensity score matching. Results Women with synchronous stage I endometrioid ovarian cancer were more likely to be diagnosed recently, be younger, have stage IA disease, grade 1 tumors, to have undergone lymphadenectomy, and were less likely to receive radiotherapy compared to those without synchronous ovarian cancer (all, P < 0.001). In a propensity score matched model, the presence of synchronous ovarian cancer was not associated with endometrial cancer-specific survival (10-year rates 96.0% versus 95.3%, P = 0.97) or overall survival (85.6% versus 87.2%, P = 0.10). Among tumors with concordant grades at the two cancer sites, survival was similar regardless of presence of synchronous ovarian tumors (grade 1 tumors, 10-year rate for overall survival, 88.2% versus 89.1%, P = 0.40; and grade 2 tumors, 84.0% versus 85.8%, P = 0.78). Conclusion Women with stage I endometrioid endometrial cancer with synchronous stage I endometrioid ovarian cancer have a survival outcome similar to those with stage I endometrioid endometrial cancer without synchronous ovarian cancer.