Stromal Tumor Infiltrating Lymphocytes (sTILs) as a putative prognostic marker to identify a responsive subset of TNBC in an Indian Breast Cancer Cohort.

ObjectivesPrognostic significance of stromal tumor infiltrating lymphocytes (sTILs) is evaluated to identify a responsive subset of TNBC in an Indian cohort of breast cancer patients. MethodsA retrospective cohort of breast cancer patients from a single onco-surgeon breast cancer clinic treated with uniform treatment strategy across is evaluated for sTILs. FFPE tissue of primary tumor of invasive breast carcinoma are collected with ethical approvals. Tumor sections blinded for subtypes are stained with H&E and scored for sTILs by a pathologist following Immuno-Oncology TILs working groups scoring guidelines. ResultsAnalysis of 144 primary breast tumors for sTILs scores re-enforces significantly higher infiltration in TNBC tumors than HER2+ and ER+ tumors. Higher sTILs scores co-relate with gradually incremental pathological response to therapy specifically in TNBC subset and with better disease-free survival outcomes. Within TNBC, older and post-menopausal patients harbor higher scores of sTILs. ConclusionDespite a small cohort of breast cancer patients, TNBC subtype reflected significantly higher scores of sTILs with better response to therapy and disease-free outcomes as compared to other breast cancer subtypes. A larger number of breast cancer patients from an Indian cohort will strengthen the findings to establish sTILs as a marker to identify a responsive subset of TNBC. Key pointsO_ST_ABSKey point 1C_ST_ABSThis is a first attempt to understand the significance of stromal tumor-infiltrating lymphocytes in a breast cancer cohort from India, where higher recurrence and mortality rates are observed. Key point 2TNBC tumors show higher sTILs infiltration compared to non-TNBC patients. Higher sTILs scores within TNBC co-relates with better therapy response disease-free survival. Key point 3Higher sTILs scores in TNBC tumors in an Indian cohort showed a novel and unique association with old age and post-menopausal patients.