Prognostic implications of residual disease (RD) tumor-infiltrating lymphocytes (TIL) in triple negative breast cancer (TNBC) after neo-adjuvant chemotherapy (NAC).

571Background: For primary TNBCs treated with NAC, higher pre-treatment TILs correlate with increased pathological complete response (pCR) rates, better recurrence-free survival (RFS) and overall survival (OS). We evaluated the prognostic value of RD TILs to pathological stage and Residual Cancer Burden (RCB) in predicting survival post NAC. Methods: We combined individual patient data from 4 TNBC patient series treated with NAC who did not achieve pCR. TILs were evaluated on the RD using our previously published method on H&E stained slides. TILs were investigated for associations with yp stage, RCB, RFS and OS using Cox models with stromal TILs as a continuous variable, stratified by series. The likelihood ratio (LR) test was used to evaluate added prognostic value of TILs to standard yp stage and RCB class. Results: In total 376 RD samples were evaluable for TILs. After 6 years median follow-up we observed 193 RFS events and 165 deaths. The median age was 50 years (range 24-83). 62% received combinatio...