Association of TILs and HER2-low status with pathological response in triple-negative breast cancer

Triple-negative breast cancer (TNBC) is the most aggressive breast cancer subtype with the lowest treatment success rate. The aim of this study is to determine the relationship between tumor-infiltrating lymphocytes (TILs) score and HER2 score in TNBC patients receiving neoadjuvant chemotherapy and its effectiveness in predicting treatment response. One hundred two patients diagnosed with TNBC, who received neoadjuvant chemotherapy and underwent surgery were included in the study. The TILs score in the tru-cut biopsies of the patients was evaluated, and pathological response rates from mastectomy materials were also examined. The pathological complete response (pCR) was observed after neoadjuvant chemotherapy in 43 (43.2%) patients, while no pCR in 58 (56.8%) patients. Chi-square analysis revealed a significant relationship between the TILs score (p: 0.001), clinical T stage (P = .019), and pCR response. In multivariate logistic regression analysis, a significant relationship was found only between TILs and pCR (OR = 13.3, 95% CI = 2.23-81.23, P = .00). No significant relationship was found between pCR and HER2 score (P = .23), Ki-67 (P = .52), grade (P = .87) and menopausal status (P = .20). No significant relationship was found in the correlation analysis between TILs and HER2 score (P = .26, CC = 0.14). TILs score in TNBC is related to both the pCR and disease prognosis. We believe that larger-scale studies are needed to identify more factors that may predict neoadjuvant treatment response in TNBC patients. Additionally, we suggest that the relationship between HER2 score and TILs score in TNBC patients should be examined in larger studies.