Prognostic significance of natural killer cell infiltration in hepatocellular carcinoma

Abstract

Several studies have Shown the correlation of high numbers of tumor-infiltrating natural killer (NK) cells with a good prognosis for cancer patients. This study was to investigate the impact of NK cell infiltration on the survival and prognosis of patients with hepatocellular carcinoma (HCC) after resection. The proportion of infiltrating NK cells of HCC patients was measured using flow cytometry, and the expression of CD56+ (NK) cells was investigated using immunohistochemistry. Prognostic values of intratumoral and peritumoral NK cell densities were evaluated by Kaplan-Meier method and Cox regression. The level of NK cells was significantly lower in tumor-infiltrating lymphocytes (TIL) of HCC patients than in nontumor-infiltrating lymphocytes (NIL) [(11.8 +/- 8.1)% vs. (18.0+/-7.9)%, P=0.002]. The density of NK cells was also significantly lower in cancer nests than in peritumoral lesions (2.3 +/- 2.6 vs. 8.5 +/- 4.5 cells per field, P<0.001). Patients with low intratumoral NK cells had shorter disease-free survival (P=0.027) and overall survival (P=0.005) than patients with high intratumoral NK cells. In contrast, NK cells in the peritumoral area showed no prognostic significance for either disease-free survival or overall survival. Multivariate Cox proportional hazards analysis showed that intratumoral NK cell density was an independent prognostic factor of prolonged overall survival (hazard ratio = 2.658, P=0.019). Low NK cells infiltration could predict poor prognosis in patients with HCC.