RESUMEN
BACKGROUND: Breast cancer comprises a highly heterogeneous subset of tumours that respond well to Neoadjuvant Chemotherapy (NAC). Tumour Infiltrating Lymphocytes (TIL) act as a means to an end by shedding light on the treatment response as well as predictive factors to the clinicopathological features for the same. Therefore, this article attempts to shift the attention to the relevance of TIL in the aforementioned aspects by bringing to notice the contrasting traits displayed by them in the different immunohistochemical subtypes of breast carcinoma. MATERIALS AND METHODS: 75 triple-negative breast cancer (TNBC) patients, 25 human epidermal growth factor receptor (HER2BC) positive patients and 77 hormone receptor (HRBC) positive breast cancer patients were included in this study who received NAC before surgical excision of the tumour which was then stained using routine Haematoxylin and Eosin techniques. Standardised guidelines were used to evaluate TIL in the stroma and the tumour. RESULTS: In TNBC, a significant association between Intratumoural (IT) TIL (p=0.0288) and Intrastromal (IS) TIL (p=0.0250) with pathological complete response (pCR). IS TIL and age at operation (p=0.0494) showed significant values but no correlation was found with IT TIL. In HER2BC, IS TIL revealed a significant association with the tumour response(p=0.0229). A strong association was found between IT TIL and the age of menopause(p=0.0441). In HRBC, no significant associations were found between IT and IS TIL scores and the clinicopathological features. CONCLUSION: The predictive factors of TIL and complete response post-neoadjuvant chemotherapy can be a strong indicative factor for immunohistochemical markers. It also helps throw light on further studies which can be carried out to determine the clinicopathological features and TIL correlation in the various subtypes of breast carcinoma.