Prevalence of breast cancer in ovarian cancer patients and its impact on patient survival: An analysis of the surveillance, epidemiology, and end results data

Background: Patients with high-grade serous ovarian carcinoma (HGSOC) often have a personal and/or family history of breast cancers. However, the clinical association and underlying molecular interaction between breast cancer and HGSOC is not well understood. In this study, the clinical characteristics and outcomes of HGSOC patients with or without breast cancer were compared. Methods: Eligible patient information was extracted from the Surveillance, Epidemiology, and End Results database. Kaplan-Meier and Cox proportional hazards regression models were used to determine survival outcomes and prognostic factors. Results: A total of 3065 HGSOC (ICD-O-3 code 8461/3) patients were identified from 1975 to 2020, among whom 239 (9.56%) had co-existing breast cancers. HGSOC with breast cancers tended to have more stage I-II ovarian cancer (20.92% vs 13.79%), less metastatic diseases (25.1% vs 32.13%) and had a higher probability of undergoing surgery (94.1% vs 87.9%). The overall survival of HGSOC patients with breast cancer was better than that of patients without breast cancer (HR = 0.77, 95% CI 0.65 to 0.91; P = 0.0015). Further, patients who developed ovarian cancer before breast cancer had better overall survival than those who developed breast cancer before or simultaneously with ovarian cancer (HR = 0.35, 95% CI 0.23 to 0.52; P < 0.001). Conclusion: HGSOC combined with breast cancer is a common phenomenon. HGSOC patients with breast cancer, especially those diagnosed with ovarian cancer before breast cancer have a better prognosis. Further validation is warranted and more genetic and mechanistical study is needed.