Prognostic impact of tumor-infiltrating lymphocytes (TIL's) and stromal-infiltrating lymphocytes (SIL's) in triple-negative breast cancer.

Abstract

83 Background: Immune response seems to improve outcome in women with Triple-Negative Breast Cancer (TNBC). Recent data suggests that the presence of Tumor-Infiltrating Lymphocytes is an independent factor associated with better prognosis. In this study, we evaluate the prognostic impact of both TIL´s and SIL´s in patients with TNBC. Methods: Data on women diagnosed with TNBC between 2005 and 2013, was collected by retrospectively reviewing at our institute. The rate of intratumoral and/or stromal lymphocytes was evaluated in all hematoxylin and eosin-stained histopathologic sections according to Denkert et al. The five-year disease-free survival (DFS) and overall survival (OS) were compared between groups with the presence or absence of TIL´s or SIL´s. Demographic and clinical characteristics were assessed, variables with a statistical significance between groups were analyzed in a multivariate analysis. Results: A total of 172 patients with TNBC treated at this institution were included with a mean age of 49.8 years. A complete absence of tumor lymphocytes was found in 88 patients while the presence of intratumoral, stromal or both was found in 84 (48.8%). A mean follow-up of 46.12 months showed significantly higher rates of both DFS and OS in women with SIL´s and TIL´s (p = 0.014 and 0.042 respectively) in locally advanced stages (LAS), regardless the rate of infiltrating lymphocytes found [Table 1]. SIL´s are correlated with a better prognosis compared with TIL´s (p = 0.028 and 0.091 respectively). Non-significant differences were found in early stages (p= 0.255). Conclusions: These results show that the presence of SIL´s or TIL´s are strongly associated with higher rates of DFS and OS in LAS, especially when SIL´s are found, suggesting that immunity seems to play a key role regarding the outcome in women with TNBC. Independent of the rate of lymphocytic infiltrate, its presence has a statistical significance. Because it is a feasible and inexpensive test that can be used as a prognostic predictor, we suggest assessing both SIL's and TIL's in histopathologic biopsies of patients with TNBC. [Table: see text]