Predictive and prognostic value of tumor-infiltrating lymphocytes in breast cancer treated with neoadjuvant chemotherapy.

Abstract

128 Background: The prognostic importance of tumor-infiltrating lymphocytes (TILs) in triple-negative (TN) and HER2-positive breast cancer has been suggested in recent trials. The aim of this study is to evaluate a relationship between TILs and response to neoadjuvant chemotherapy (NAC) as well as long-term outcome in breast cancer including luminal, TN and HER2 subtypes. Methods: Twenty-seven patients receiving NAC from January 2010 to March 2015 at Inagi Municipal Hospital were analyzed. Intratumoral lymphocytes (ItuLy) and stromal lymphocytes (StrLy) were evaluated in hematoxylin and eosin-stained sections from pretherapeutic core needle biopsies. Lymphocyte-predominant breast cancer (LPBC) was defined as tumors with > 50% of ItuLy or StrLy. Results: A total of 27 patients were divided into 13 luminal (48.1%), 3 TN (11.1%) and 11 HER2 (40.7%) subtypes. The median age was 58 years and the median tumor size was 3.0 cm. A significant correlation between ItuLy (the median percentage: 5%) and StrLy (25%) was observed (Pearson correlation coefficient = 0.628, P< 0.01). LPBC comprised 29.6% (8/27) of total population, with higher frequencies of 33.3% and 54.5% in the TN and HER2-positive subtypes, when compared with 7.7% in luminal subtype (P= 0.044). LPBC group had a significantly higher pathological complete response (pCR) rate of 62.5% (5/8), compared with 5.3% (1/19) for non-LPBC group (P= 0.004). LPBC showed the modest correlation with pCR in luminal (100% (1/1) vs. 0% (0/12), P= 0.077) and HER2-positive subtypes (66.6% (4/6) vs. 25% (1/5), P= 0.175). In TN subtype, neither LPBC nor non-LPBC showed pCR. After a median follow-up of 24.3 months, patients with any TILs were significantly associated with better disease-free survival (DFS) than those without TILs (24.3 vs. 23.6 months, P= 0.016). The most significant impact of TILs on DFS was observed in HER2-positive subtype (23.2 vs. 15.2 months, P= 0.046), whereas TILs did not associate with DFS in luminal and TN subtypes. Conclusions: The presence of TILs was a significant predictor for response to NAC and would provide useful information of prognosis in breast cancer.