Epidemiology of Triple Negative Breast Cancer among Cancer Breast Patients and Their Relation to Molecular and Histological Subtypes of Cancer Breast in A Tertiary Care Centre

Background: A unique subtype of breast cancer called triple-negative breast cancer (TNBC) is distinguished by the lack of expression of the HER2 (human epidermal growth factor receptor 2), PR (progesterone receptor), along with ER (estrogen receptor). In comparison with other subtypes of breast cancer, TNBC has been linked to a worse prognosis and an aggressive clinical course. The goal of this retrospective research is to assess the incidence of TNBC among breast carcinoma patients at a tertiary care hospital, in Chennai. This research also highlights histopathological characteristics and molecular subtypes observed within the sample population. Methodology: This retrospective analysis was conducted among carcinoma breast patients who presented to the Department of General Surgery, Chettinad Hospital and Research Institute, in the Chennai between January 2021 and January 2024, underwent histopathological testing either by TRUCUT Biopsy or surgical resection. In this study, 58 patients with breast cancer were identified of which 2 were excluded because of lack of PR, ER, HER2/neu status. Statistical analysis was conducted utilizing IBM SPSS version 22. Results: Overall, 56 cases had been included in our research, Of the 56 patients, 19 (33.92%) were triple negative breast carcinoma. The most common histologic variant was noted to be infiltrating ductal carcinoma (IDC) of no specific type comprising a 64.28% (n=32) of all breast cancers, followed by ductal carcinoma in situ (DCIS) and papillary carcinoma each comprising 12.5% (n=7). Other variants noted included infiltrating ductal carcinoma with medullary changes (8.9%), mucinous adenocarcinoma (3%), a case of apocrine carcinoma (1.7%), and a case of tubular carcinoma (1.7%). Conclusion: This analysis reveals a higher than average number (33.92%) of TBNC patients in a tertiary hospital, which is in line with the studies done globally. This research demonstrated the need to develop tools to accurately and quickly ascertain the molecular subtypes of breast cancer to guide effective management. Further investigation is necessary to clarify biological and epidemiological factors contributing to the high prevalence of TNBC in this setting.