Impact of tumor-infiltrating lymphocytes on pathological complete response after neoadjuvant chemotherapy in patients with early triple-negative breast cancer

Description of the subject: Triple-negative breast cancer (TNBC), a breast cancer subtype, is characterized by the lack of both estrogen and progesterone hormonal receptors expression and by the absence of human epidermal growth factor receptor 2 overexpression. Patients with a pathological complete response (pCR) have better disease-free and overall survival compared to those with residual disease. The high level of tumor-infiltrating lymphocytes (TILs) is associated with a higher response to neoadjuvant chemotherapy (NAC) and better prognosis. Objective: Evaluation of TILs and their predictive impact in early TNBC in an Algerian population. Methods: We assessed TILs and correlated them with the pCR rate in 94 early TNBC patients treated from 2015 to 2017 who underwent breast microbiopsy, NAC, and then surgery. Results: Among 94 early TNBC patients, 53 (56.4%) achieved pCR and 41 (43.6%) had a residual disease. While some clinicopathological factors did not affect pCR, stromal TILs showed significant correlation with pCR (P < 0.0001). The presence of CD3+, CD4+, CD8+ and CD20+ TILs was also significantly correlated with pCR (P < 0.0001, P = 0.001, P = 0.0003 and P = 0.0001, respectively). Conclusion: Our data showed that TILs were significantly associated with pCR, suggesting that TILs are a predictive biomarker for pCR in early TNBC patients treated by NAC in our cohort