Do Tumor-Infiltrating Lymphocytes Predict Complete Pathologic Response to Neoadjuvant Systemic Therapy in Breast Cancer Patients?

Neoadjuvant systemic treatment for breast cancer is used in locally advanced and operable breast cancer. Standard neoadjuvant systemic therapy regimens for breast cancer patients include anthracycline based chemotherapy (Doxorubicin/Cyclophosphamide) followed by taxanes (weekly Paclitaxel or Docetaxel) with antiHer-2 Trastuzumab or dual antiHer-2 Trastuzumab plus Pertuzumab. Other regimens include Docetaxel plus Carboplatin plus Trastuzumab alone or combined with pertuzumab for Her-2 positive patients.

The tumor microenvironment, which includes extracellular matrix and stromal cells, is a key factor in tumorigenicity and the prediction of the efficacy of immunotherapy, conventional chemotherapy, and other anticancer therapies. Tumor-infiltrating lymphocytes (TILs), one of the most important components of the tumor microenvironment, were reported to predict the response to NAC both for tumors and axillary lymph nodes in breast cancer patients. This study is conducted to examine the relationship between tumor-infiltrating lymphocytes (categorized into three levels) and the pathologic complete response to neoadjuvant systemic therapy in breast cancer patients, and to examine the relationship between TILs and 1-year invasive disease-free survival (IDFS).