A Retrospective Study on the Clinicopathologic Characteristics and Outcomes of 179 Cases of Synchronous and Metachronous Bilateral Breast Cancer in China

To investigate the clinicopathologic characteristics and outcome of bilateral breast cancer (BBC) in the Chinese population.A retrospective study was conducted on 7797 cases with primary breast cancer, including 7618 cases of unilateral breast cancer (UBC) and 179 cases of BBC. Among the latter, there were 108 cases of synchronous BBC (SBBC) and 71 cases of metachronous BBC (MBBC).In the present study, the incidence of SBBC and MBBC are 1.39% and 0.91% among the general population, respectively. In comparison of UBC and BBC, SBBC and MBBC, there are significant differences in the common clinicopathological characteristics, such as pathologic stage, hormone receptor (HR) status and molecular type. In respect of the surgical treatment of BBC, 49.72% of the patients chose mastectomy. The 3-year disease free survival (DFS) for SBBC and MBBC are 94.4% and 96.9%, respectively. There is no difference in the overall survival (OS) and DFS between SBBC and MBBC. The histological grade and type of surgery on tumors of both sides are important influencing factors of DFS in the BBC patients.There are statistical differences in the clinicopathological characteristics and outcomes between SBBC and MBBC among the Chinese population. Therefore, the treatment of BBC patients should be individualized.