28590 – PREDICTIVE VALUE OF TUMORINFILTRATING LYMPHOCYTES FOR RESIDUAL DISEASE IN TRIPLE-NEGATIVE BREAST CANCER IN PATIENTS AFTER NEOADJUVANT CHEMOTHERAPY

Abstract

Introduction: The evaluation of tumor-infiltrating lymphocytes (TILs) has been widely studied in the pretreatment setting. However, the prognostic role of TILs in residual disease after neoadjuvant chemotherapy (NAC) involving immune
changes in the tumor microenvironment remains under debate. Methodology: Slides from stage II and III triple-negative tumors between 2008 and 2019 of patients with residual disease after NAC were analyzed. Stromal TILs were assessed at two time points: pre-NAC and post-NAC. TIL counts were performed according to the recommendations of the
International TILs Working Group, analyzed as a continuous measure and divided into two categories: high infiltration
with ≥30% of the area infiltrated by lymphocytes, and low infiltration when the area was <30%. Conclusion: The increase in TIL infiltration after NAC may help identify additional immunogenic characteristics presented by residual triple-
-negative breast cancer induced by treatment. The differentiation of patients who do not achieve pathological complete
response (pCR) but exhibit favorable immunological tumor characteristics (increase in TILs) can assist in better selecting
patients who would benefit from complementary therapies focused on the immune system..