Synchronous/Metachronous Bilateral Breast Cancer: a Long-Term Follow-up Single-Center Experience

We aimed to evaluate the ratio of bilateral breast cancer (BBC) to breast cancer and to compare the clinicopathological characteristics, treatment, and results of synchronous bilateral breast cancer (sBBC) and metachronous bilateral breast cancer (mBBC) with long-term follow-up. Patients with breast cancer (BC) who were treated consecutively between 2009 and 2019, included on accrual records, were examined. We determined the time interval for the development of two tumors to be detected within 6 months for the definition of synchronous tumors. In total, of the 2198 patients diagnosed with BC, 76 had BBC. Our BBC rate was 3.4%. The median age of tumor detection was 56 for sBBC and 51 for mBBC. As a result of the 5-year disease-free survival (DFS) analysis, the mean survival times of sBBC and mBBC were found to be 41 months and 60 months, respectively (p = 0.006). As a result of the 5-year overall survival (OS) analysis, the OS in sBBC and mBBC was 44 months and 60 months, respectively, and the difference in mean survival times between the groups was statistically significant (p = 0.001). The difference between the sBBC and mBBC groups was statistically significant for both DFS and OS, based on 10-year survival (p = 0.004 and p = 0.001, respectively). In this study conducted at a single center, disease-free survival and overall survival were worse in sBBC than in mBBC.