Second Primary Ovarian Epithelial, Fallopian Tube, and Primary Peritoneal Cancers after Breast Cancer Diagnosis: Korea Central Cancer Registry

PURPOSE: A prior history of breast cancer is a risk factor for the subsequent development of primary peritoneal, epithelial ovarian, and fallopian tubal (POFT) cancers. This study aimed to estimate the incidence of secondary POFT malignancy in breast cancer patients and the clinical outcomes of primary and secondary POFT cancer. MATERIALS AND METHODS: We searched the Korea Central Cancer Registry to find patients with primary and secondary POFT cancer who had breast cancer in 1999–2017. The incidence rate and standardized incidence ratio were calculated. Additionally, we compared the overall survival of patients with primary and secondary POFT cancer. RESULTS: Based on the age-standardized rate, the incidence of second primary POFT cancer after breast cancer was 0.0763 per 100,000 women, which increased in Korea between 1999 and 2017. Among the 30,366 POFT cancer patients, 25,721 were primary POFT cancer only, and 493 had secondary POFT cancer after a breast cancer diagnosis. Second primary POFT cancer patients were older at the time of diagnosis (55 vs. 53, p < 0.001) and had a larger proportion of serous histology (68.4% vs. 51.2%, p < 0.001) than patients with primary POFT. There were no differences between the two groups in tumor stage at diagnosis. The 5-year overall survival rates were 60.2% and 56.3% for primary and secondary POFT cancer, respectively (p=0.216). CONCLUSION: The incidence of second primary POFT cancer after breast cancer increased in Korea between 1999 and 2017. Besides, second primary POFT cancer patients were diagnosed at older ages and had more serous histology.