Outcome Prediction After Neoadjuvant Chemotherapy (NAC) for Breast Cancer, Using Tumor-infiltrating Lymphocytes Within Fibrotic Foci of Tumor Stroma (FF-TILs)

Abstract

Background/Aim: Tumor-infiltrating lymphocytes (TILs), which are indicators of immune response monitoring, are generally mononuclear immunocytes that aggregate with tumors and are thought to have a close relationship with cancer cells. On the other hand, a fibrotic focus (FF) within the stroma of a tumor is a histological formation that plays an important role in the cancer microenvironment with regard to proliferation and development. Here, we focused on TILs that exist within the FF and performed pathological evaluations. Patients and Methods: Of the 320 patients treated with neoadjuvant chemotherapy (NAC), 239 subjects who were able to evaluate FF-TILs were targeted. Lymphocytes that infiltrate the FF are FF-TILs. Results: The disease-free survival (DFS) period after NAC for the high-FF-TIL group was found to be significantly longer than that for the low-FF-TIL group for all cases (p<0.001) and for all subtypes of triple-negative breast cancer (TNBC) (p=0.001), human epidermal growth factor receptor 2-enriched breast cancer (HER2BC) (p=0.010), and hormone receptor-positive breast cancer (HRBC) (p=0.003). In multivariable analysis as well, high-FF-TIL group classification was an independent factor for recurrence after NAC for all cases [p<0.001, hazard ratio (HR)=0.198] and all subtypes of TNBC (p=0.006, HR=0.172), HER2BC (p=0.025, HR=0.135), and HRBC (p=0.007, HR=0.228). Conclusion: FF-TILs are possibly a useful factor for predicting recurrence of breast cancer after NAC.