Histopathological Evaluation of Tumor-Infiltrating Lymphocytes (TILs) as Predictive Biomarker for Hormone Receptors Status, Proliferative Activity and Clinical Outcome in Her-2 Positive Breast Cancer

Background: In the present study, we evaluated the prognostic value of TILs as well their relation with clinicopathological factors in patients affected by HER-2 positive breast cancer. Methods: We evaluated 47 patients with a histologically confirmed diagnosis of invasive breast carcinoma showing an immunohistochemically confirmed (score 3+) amplification of the c-erbB-2 gene for the presence of TILs and categorized in three predefined groups of low (0–10% immune cells in stromal tissue within the tumor), intermediate (11–40%), and high TILs (>40%). Results: Low, intermediate and high TILs were found in 17/47 (36%), 23/47 (49%) and 7/47(15%) cases, respectively. It was found that 6/47 cases treated with adjuvant chemotherapy plus trastuzumab underwent progression of the disease; none of these cases exhibited high TILs. It was found that 12/47 patients with a prognostically unfavorable stage of III and IV showed low and intermediate levels of TILs, while high TILs were never observed. A significant association between intermediate/high-levels of TILs, elevated KI 67 index and hormone receptors nuclear staining was observed. High concordance in TILs distribution was observed between preoperative breast biopsies and surgical samples. Conclusions: We observed a positive correlation between the TILs and the response to both adjuvant and neoadjuvant treatments in HER-2 positive BC. High TILs were also related to increased KI-67 index and to the expression of hormone receptors.