Intratumoral regulatory T cells alone or in combination with cytotoxic T cells predict prognosis of hepatocellular carcinoma after resection

Tumor-infiltrating lymphocytes (TILs) represent the host immune response to cancer. CD8(+) cytotoxic T cells (CTLs) have a central role in the elimination of tumors, while regulatory T cells (Tregs) can suppress the immune reaction. The aim of this study was to investigate the prognostic value of TILs, especially Tregs and CTLs, in hepatocellular carcinoma (HCC) patients after resection. CD3(+), CD4(+), CD8(+), and FoxP3(+) TILs were assessed by immunohistochemistry in tumor tissue from 141 randomly selected HCC patients. Prognostic effects of low- or high-density TIL subsets were evaluated by Kaplan-Meier and Cox regression analysis using the median values as cutoff. The density of intratumoral Tregs (P = 0.040) and peritumoral CTLs (P = 0.004) were an independent factor for overall survival (OS), but not for disease-free survival (DFS). The density of CD3(+) and CD4(+) TILs, and the prevalence of Tregs and CTLs were associated with neither OS nor DFS. The presence of low intratumoral Tregs with high intratumoral CTLs was a negative independent prognostic factor for OS (P = 0.001), while that of low intratumoral Tregs and low peritumoral CTLs independently correlated with improved DFS (P = 0.008). Moreover, the combined analysis of Tregs and CTLs displayed better prognostic performances than any of them alone. Additionally, higher density of intratumoral Tregs correlated with both the presence of liver cirrhosis (P = 0.025) and increased tumor size (P = 0.050). Tregs within tumor environment are promising prognostic parameters for HCC patients, and their combination with CTLs can predict prognosis more effectively.