138 Background: Whether tumor-infiltrating lymphocytes (TILs) predict response to neoadjuvant chemotherapy (NAC) remains elusive. Methods: A systematic review and meta-analysis was undertook to establish the relationship between TIL and pathological complete response (pCR) rate in NAC of breast cancer. A PubMed and Web of Science literature search was designed. Studies were included, in which the predictive significance of intratumoral and/or stromal TIL, and/or CD3+, CD4+, CD8+, and FOXP3+ lymphocytes were determined . Pooled ORs and publication bias was evaluated by STATA software. Results: A total of 13 published studies (including 3,555 patients) were eligible. In pooled analysis, higher number of TIL in pre-treatment biopsy was correlated with higher pCR rate of neoadjuvant chemotherapy, and odds ratio (OR) was 3.82 (95% confidence interval (CI), 3.10-4.70), no matter tested in intratumor (OR=3.32, 95% CI: 2.52-4.37), in stroma (OR=4.15,95% CI: 2.94-5.86), or in combined sites (OR=8.98, 95% CI: 3.79,21.30). Moreover, TIL predicts higher pCR rate in triple negative (OR=5.03,95% CI: 2.31-10.97) and HER2+ (OR=5.54,95% CI: 1.39-22.12) patients, but not in hormonal receptor (HR) +/HER2- patients (OR=2.57, 95% CI: 0.20-33.24). For TIL subsets, CD8+ T-lymphocytes predict better pathological response to NAC no matter in pre- (OR=3.36,95%CI: 1.15-9.85) or post-NAC (OR=4.71,95%CI: 1.29-17.27) tissue, while FOXP3+ T-lymphocytes have similar predictive roles only when tested after NAC (OR=4.26, 95%CI: 1.83-9.92).With limited study, the predictive role of CD3+ and CD4+T-lymphoctes were unclear, more perspective studies were needed in future to establish the relationship. Conclusions: High level of TIL in pre-treatment biopsy could be a good marker indicates better pathological response to NAC in triple-negative and HER2+ breast cancer patients. Different subsets have different predictive roles in the pCR rate to NAC. However, significant heterogeneity and an insufficient number of studies underscore the need for further prospective studies on subsets of T lymphocytes and different subtypes of breast cancer to increase the robustness of the analyses.
The Value of Tumor Infiltrating Lymphocytes (TILs) for Predicting Response to Neoadjuvant Chemotherapy in Breast Cancer: A Systematic Review and Meta-Analysis
