Bilateral Breast Cancer After Multimodality Treatment: A Report of Clinical Outcomes in an Asian Population

Bilateral breast cancer (BBC) is an uncommon presentation. The characteristics and outcomes of synchronous and metachronous BBC were compared within an Indian cohort.This was a retrospective audit of 193 BBC patients treated at a tertiary hospital in India over a period of 10 years from January 2004 to December 2014. The demographic, tumor and treatment characteristics were compared between synchronous (n = 131 patients) and metachronous tumors (n = 62 patients) using descriptive analysis. The survival outcomes were assessed using Kaplan-Meier survival curves and compared using the log rank test. Univariate and multivariate analysis was done using a Cox proportional hazards model to assess the effect of the prognostic factors on survival.The mean age of presentation in synchronous BBC (SBBC) and metachronous BBC (MBBC) was 55 years (SD, 12.5) and 51 years (SD, 9.5), respectively. The median time to contralateral presentation in MBBC was 3.8 years. Mean tumor size was larger in SBBC (P = .01). Breast Cancer gene mutation was positive in 13 of 38 evaluated patients (of whom 12 had MBBC). The concordance rates for the estrogen receptor (ER) and progesterone receptor negativity and triple-negative receptor status were higher in MBBC compared with SBBC (P .001). Grade III tumor was more frequently seen in MBBC (P = .03). The median follow-up of the entire cohort was 42 months (range, 30-60 months): 45 months for SBBC and 35 months for MBBC. The 3-year rates of overall survival (OS), disease-free survival (DFS), and locoregional control (LRC) for SBBC and MBBC was 88% and 90%, 74% and 64% and 90% and 84%, respectively. There was no difference in overall OS, DFS, and LRC between SBBC and MBBC.BBC is an uncommon presentation. Synchronous presentation was more common. Metachronous tumors differ from synchronous with higher Grade of presentation and less expression of ER. There was no difference in outcome between patients with synchronous and metachronous tumors.