Clinicopathological Characteristics, Treatment and Outcome of 123 Patients with Synchronous or Metachronous Bilateral Breast Cancer in a Swiss Institutional Retrospective Series

Abstract

Objective: To evaluate the prognosis, the patient and tumor characteristics, and the treatment of bilateral breast cancer (BBC) and to compare synchronous (sBBC) and metachronous BBC (mBBC).Materials and Methods: For this retrospective study, data from 123 consecutive BBC patients (56 sBBC and 67 mBBC) that were presented at the SionHospital tumor board between 2007 and 2018 were collected retrospectively.Results: Mean follow-up was 85 months. $2^{nd}$ tumors in both groups were more often diagnosed radiologically. Mean time interval between mBBC was115 months. A shorter interval was positively correlated with a negative hormonal receptor (HR) status and higher grade for the $2^{nd}$ tumor. There was nodifference in overall survival (OS) and relapse-free survival (RFS) between sBBC and mBBC. OS was longer if both tumors were hormonal receptor (HR)positive. mBBC exhibited a higher local recurrence rate than sBBC (p=0.03).Conclusion: sBBC and mBBC patients did not show any difference in OS or RFS, although mBBC patients were more prone to local relapses.