28591 – EVALUATION OF THE PREDICTIVE ROLE OF TUMOR-INFILTRATING LYMPHOCYTES IN PATIENTS WITH HER-2 POSITIVE BREAST CANCER

Abstract

Introduction: The increase in pretreatment tumor-infiltrating lymphocytes (TILs) in patients with human epidermal
growth factor receptor 2 (HER-2) positive breast cancer has been studied in recent years, showing a positive and independent association with future pathological complete response (pCR). Methodology: Histological slides of HER-2 positive
breast tumors, stages II and III, between 2008 and 2019 were analyzed. Stromal TILs were assessed pre-NAC. TIL counts
were performed according to the recommendations of the International TILs Working Group, divided into two categories: high infiltration ≥30% of the area infiltrated by lymphocytes; and low infiltration, or <30% of the area infiltrated.
Conclusion: The possibility of predicting pathological complete response (pCR) based on immunological characteristics
can assist in better classifying which breast cancer patients have a higher likelihood of response to neoadjuvant treatments.