Objective To evaluate the prognostic value of radiation-induced lymphocytopenia in the survival of patients with primary hepatocellular carcinoma receiving radiation therapy.

Methods The clinical data of 98 patients with unresectable primary hepatocellular carcinoma who received radiotherapy were retrospectively analyzed. The minimum absolute lymphocyte count (min ALC) was graded in accordance with CTCAE V4.0. The optimal threshold of min ALC for prognosis was calculated by using the receiver operating characteristic curve, and the correlation of min ALC with clinical characteristics and dosimetry parameters was analyzed. The Kaplan-Meier method was employed to analyze the survival of patients with different levels of min ALC. Univariate and multivariate Cox proportional regression models were applied to analyze prognostic factors.

Results The baseline and min ALC of 98 patients during radiotherapy were 1.52×10⁹/L and 0.45×10⁹/L, respectively(P<0.001). The optimal cut-off value of min ALC for the prediction of the one-year survival rate was 0.38×10⁹/L. GTV, the mean dose of the liver and spleen, the V5 and V10 of the liver and spleen, and the V15 of the spleen were correlated with min ALC, and the V5 of the liver was an independent predictor of min ALC. The overall survival of patients with high min ALC was higher than that of patients with low min ALC. Independent prognostic factors were min ALC≤0.38×10⁹/L (HR=0.515, P=0.024), min ALC≥grade 3 (HR=0.576, P=0.032), tumor thrombus in the portal/vena cava, Child-Pugh grade A, increase of ≥2 points in the Child-Pugh score after radiotherapy, and received more than two other therapies.

Conclusion Min ALC≤0.38×10⁹/L and min ALC≥grade 3 have independent prognostic value in patients with unresectable hepatocellular carcinoma receiving radiotherapy.