Evaluation of Tumor infiltrating lymphocytes in breast carcinoma and their correlation with molecular subtypes, tumor grade and stage.

BACKGROUND: Tumour infiltrating lymphocytes (TILs) exhibit the local immune response directed against tumor growth and metastasis. TILs have emerged as a tool to assess immune-reactivity in various malignancies including colon, ovary, lung, bladder, breast etc as well as independent marker of favourable prognosis in many tumors. TILs in breast cancer (BC) play a role in tumor response to therapy in the adjuvant and neoadjuvant settings, especially in triple-negative cancers. MATERIAL & METHODS: This cross sectional study comprised of 101cases of invasive breast carcinoma. For each case, a representative 5 mum H&E stained section was selected and the clinicopathological details were recorded. To establish the molecular subtype of breast cancer, immunohistochemistry for ER, PR and Her2neu was done. Both stromal (sTIL) and intratumoral (iTIL) TILs were assessed based on the recommendations of the International TIL Working Group (ITILWG). RESULTS: A statistically significant difference was observed in the mean sTIL as well as iTIL scores and tumor grade, size, molecular type and lymph node metastasis. A signification correlation was observed between stromal TIL and tumor grade, lymph node metastasis, molecular subtype and mitotis. Intratumoral TIL showed a significant correlation with tumor size, mitosis, tumor grade, distant metastasis, stage and lymph node metastasis. Moreover, stromal and intratumoral TIL showed a highly significant correlation with each other. CONCLUSION: The IWTILG recommendations are reproducible and reliable for the evaluation of sTILs and iTILs. TILs, as evaluated on Hematoxylin and eosin (H&E) slides, has been shown in numerous studies now to be a reliable, reproducible, inexpensive and readily available marker of pre-existing antitumor immunity in breast cancer. We suggest that TILs should be evaluated for each case of breast carcinoma and should be part of histopathology report.