The time interval rules and survival outcomes of individuals with synchronous and metachronous breast cancer (BC) and ovarian cancer (OC) were examined in this retrospective population-based investigation.The National Cancer Institute's Surveillance, Epidemiology, and End Results database was used to create a cohort of people diagnosed with BC and OC between 1973 and 2015. Patients were separated into three groups: those with main BC followed by primary OC (group 1), those with synchronous primary breast and ovarian cancer (group 2), and those with OC prior to BC (group 3). The Kaplan-Meier technique was used to assess overall survival (OS) and cancer-specific survival (CSS).A total of 4,975 patients were identified: 2,929 patients in group 1, 680 patients in group 2, and 1,366 patients in group 3. The average duration between these tumors was 60 months (range 0-499). Approximately 50% of second primary cancer cases occurred during the first 60 months of the first primary cancer diagnosis, and more than 70% occurred within the first 120 months. The median survival time for 4,975 individuals was 140 months. Group 2 had the smallest median OS (35 months), whereas group 3 had the longest (45 months) (239 months).The majority of second primary cancer cases occurred during the first 120 months following the diagnosis of the first original malignancy. Individuals who had primary OC prior to BC had better prognoses, whereas patients who had synchronous BC and OC had worse prognoses.Copyright © 2022 Xin-Qin He et al.