Tumor-Infiltrating Lymphocytes (TILs) and Risk of a Second Breast Event After a Ductal Carcinoma in situ
Alberto Farolfi, Elisabetta Petracci, Luigi Serra, Alessandra Ravaioli, Sara Bravaccini, Sara Ravaioli, Maria Maddalena Tumedei, Paola Ulivi, Matteo Canale, Maurizio Puccetti, Fabio Falcini, Secondo Folli, Annalisa Curcio, Andrea Rocca
Abstract
Women with a diagnosis of ductal carcinoma in situ (DCIS) have a high risk of developing a second breast event (SBE). The immune system might play a role in trying to prevent a SBE. Patients diagnosed with DCIS were identified in the population-based cancer registry of Area Vasta Romagna from 1997 to 2010. Median follow-up is 8.5 years. Tumor-infiltrating lymphocytes (TILs) were evaluated both in index DCIS and in SBE. The main endpoint was to assess the association between TILs' levels in index DCIS and risk of a SBE. Out of 496 DCIS patients, 100 SBEs (20.2%) were identified: 55 ipsilateral (11.1%) and 43 contralateral (8.7%). The distribution of TILs was heterogeneous, but significantly associated with grade, necrosis, screen detection and type of surgery. Patients stratified according to TILs percentage (≤ 5% and > 5%) did not show a statistically significant difference in the 5-year cumulative incidence of SBEs: 14.9% (95% CI 11.3-19.1) and 11.0% (95% CI, 6.9-16.2), respectively (p = 0.147). In the subgroup of patients who did not receive radiotherapy, TILs >5% were associated with a reduced risk of SBE (HR 0.34, 95% CI 0.14-0.82, p =0.016). Although we did not find any significant association between TILs and SBE, further studies evaluating their role according to radiotherapy are warranted.