Histobiologic comparative analysis is insufficient to differentiate second primary from metastasis in bilateral breast cancer

Abstract

Author(s): Sithara Aravind, Deepak Roshan V.G*, Vinin N.V and Sangeetha K. Nayanar

Bilateral Breast Cancer (BBC) is a rare clinical entity. BBC is termed as Synchronous Breast Cancer (SBC) if second breast cancer occurs within 6 months and Metachronous Breast Cancer (MBC) if it occurs after 6 months of diagnosis of first breast cancer. Unlike Unilateral Breast Cancer (UBC), there is limited data regarding BBC in Indian population. Hence, we carried out are retrospective single centre study. 5 years (Jan 2012-Dec 2016) data of patients diagnosed with BBC retrieved from Institutional Cancer Registry. A total of 34 cases of BBC were included in the study, of which 18 were SBC. Mean age of presentation was 51 years, 64.7% being postmenopausal. First tumour predominated in left breast (65%) with Invasive Ductal Carcinoma as predominate histological type. Results showed 85%, 68% and 80% of concordance in ER, PR and HER2 status between the first and second tumour, respectively. Modified radical mastectomy was the most common surgical treatment (65%) received by the patients. Adjuvant treatment was given to 70% of patients. Mean follow up period was 29 months, 15 patients had disease free survival of 5 patients with recurrence, 3 were found to be SBC. SBC show an increased incidence of distant metastasis (9 of 10) and significantly poor overall survival, even early stage SBC showed poor overall survival. A histobiological concordance assessment between the two tumours of MBC and SBC with respect to ER, PR, HER2 status and histological type showed similar pattern of concordance. Hence, ER, PR, HER2 status, histological types and duration between first and second tumour may not be sufficient for labelling second tumour as a new primary/ metastasis. Genetic profiling and additional molecular approaches has to be applied to solve the debate.

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