No impact of smoking status on breast cancer tumor infiltrating lymphocytes, response to neoadjuvant chemotherapy and prognosis

ABSTRACT INTRODUCTION Tobacco use is associated with an increase in breast cancer (BC) mortality. Pathologic complete response rate to neoadjuvant chemotherapy (NAC) is influenced by tumor-infiltrating lymphocytes (TILs) levels and is associated with a better long-term survival outcome. Whether tobacco modifies either tumoral microenvironment such as TIL levels, either pCR rates remains unclear. The aim of our study is to evaluate the impact of smoking status on TIL levels, response to NAC and prognosis for BC patients. METHODS We retrospectively evaluated pre and post NAC stromal and intra tumoral TIL levels and pCR rates on a cohort of T1-T3NxM0 BC patients treated with NAC between 2002 and 2012 at Institut Curie. Smoking status (current, ever, never smokers) was collected in clinical records. We analyzed the association between smoking status, TIL levels, pCR rates and survival outcomes among the whole population, and after stratification by BC subtype. RESULTS A total of 956 BC patients with available smoking status information were included in our analysis [current smokers, n=179 (18.7%); ever smokers, n=154 (16.1%) and never smokers, n = 623 (65.2%)]. Median pre-NAC TIL levels, pCR rates, or median post-NAC TIL levels were not significantly different according to smoking status, neither in the whole population, nor after stratification by BC subtype. With a median follow-up of 101.4 months, relapse free survival (RFS) and overall survival (OS) were not significantly different by smoking status. CONCLUSION In this study, we did not find any significant effect of tobacco use on pre and post NAC TILs nor response to NAC and. Though our data seem reassuring, BC treatment should still be considered as a window of opportunity to offer BC patients accurate smoking cessation interventions.