Tumor-infiltrating lymphocytes are significantly associated with better overall survival and disease-free survival in triple-negative but not estrogen receptor-positive breast cancers.

Correlation between tumor-infiltrating lymphocytes (TILs) and complete pathological response (pCR) in breast cancers in neoadjuvant settings have been reported. In this study, we analyzed the association between TILs and diagnostic and prognostic parameters in estrogen receptor-positive (ER+) and triple-negative breast cancer (TNBC) without neoadjuvant treatments. Three hundred forty-four (344) patients who underwent mastectomy for breast cancer (187 ER+ and 157 TNBC) without neoadjuvant treatments were evaluated. Percentage of overall and peripheral TILs were correlated with lymphovascular invasion (LVI), Nottingham histologic grade (NHG, 1/2 versus 3), stage, lymph node status (LN), overall survival (OS), and disease-free survival (DFS). In TNBC, both peripheral and overall TILs were significantly associated with NHG 3 (P<.0001). Peripheral but not overall TILs were significantly associated with better OS (hazard ratio [HR]: 0.95; 95% confidence interval [CI]: 0.91-1.00; P=.0354) and DFS (HR: 0.95; 95% CI: 0.91-1.00; P=.0314) in univariate and multivariate analysis. In ER+ breast cancer, only peripheral TILs were associated with NHG 3 (P=.018) but not with OS or DFS (both P>.05). In ER+ breast cancer, there was a negative association between Oncotype DX recurrence score and both overall (P=.0007) and peripheral TILs (P=.0119). In conclusion, peripheral but not overall TILs correlate with better OS and DFS in TNBC, indicating the location of TILs may be important in TNBC. The negative association between TILs and Oncotype DX score in ER+ may indicate the possible prognostic value of TILs in ER+ breast cancer.