Stromal Tumor infiltrating lymphocytes (sTILs) as a prognostic biomarker in Ovarian Cancer After Neoadjuvant chemotherapy.

OBJECTIVE: The aim of the study was to evaluate the prognostic impact of sTILs on survival in a specific cohort of patients of high grade serous epithelial ovarian cancer following interval cytoreductive surgery ± HIPEC.

MATERIAL AND METHOD: Formalin fixed, paraffin embedded (FFPE) tumor tissue of high grade serous ovarian cancer of 168 patients, undergoing interval cytoreductive surgery were evaluated by dedicated oncopathologists. The average stromal TIL percentage was calculated for each patient, for ovary and omentum. To determine a threshold for TILS in Ovarian cancer which can serve as a reference value for validation as a prognostic biomarker, we applied maximally distributed rank statistics using the 'maxstat' package from 'R-stats'. Overall survival was the endpoint for measuring prognosis. The prognostic significant of TILs on survival was determined using univariable log rank test and multivariable cox-regression analysis.

RESULT: The Intraclass coefficient for sTILS in the ovary was 0.882 [95 %CI 0.85-0.90] and 0.93 for sTILs in the omentum was 0.93 [95 %CI 0.91-0.95] showing that there was good interobserver agreement between the pathologist. Threshold for sTILS was 20 % for the ovary and 26 % for the omentum. sTILS in the ovary separated by the cut-off 20 %, showed an improvement in overall survival (OS) in both univariate as well as multivariate analysis. (Log rank 0.97 (0.94-0.99, p = 0.007), cox regression analysis, [HR 0.96 (95 %CI 0.93-0.99, p = 0.003) ] respectively.

CONCLUSION: While our study provides some evidence for the prognostic role of sTILs in advanced high-grade serous epithelial ovarian cancer, the determined cut-off threshold warrants additional validation in future studies.