Intratumoral and peritumoral lymphocytic responses correlate with survival in rectal cancer

Abstract

Background: Colorectal cancer (CRC) with high level of microsatellite instability (MSI-H) is associated with improved survival. Histopathological assessment of prominent infiltration of lymphocytes in tumor microenvironment (TME), including intratumoral lymphocytic response (ILR) and peritumoral lymphocytic response (PLR), was utilized to predict MSI-H. However, the direct pathological evidence of lymphocytic response predicting survival of rectal cancer is lacking due to the predominant neoadjuvant concurrent chemoradiotherapy (CCRT) treatment. This study aims to identify whether the phenotype of PLR and ILR is associated with the clinical outcome of locally-advanced rectal cancer receiving definitive surgery followed by adjuvant CCRT.