Minimum absolute lymphocyte counts during radiation are associated with a worse prognosis in patients with unresectable hepatocellular carcinoma

Background: Peripheral blood lymphocytes play an important role in antitumour immunity. We examined the relationship between the minimum absolute lymphocyte counts (Min ALCs) during radiotherapy (RT) and clinical outcomes in patients with hepatocellular carcinoma (HCC). Methods: Data from a total of 69 HCC patients who had received RT were retrospectively analysed. Peripheral blood lymphocytes were measured before RT, weekly during RT and after RT. Regression and mixed-effect models were used to assess the relationships with and potential predictors of overall survival (OS). Receiver-operating characteristic (ROC) curve analysis was used to define optimal cut-off points of continuous variables for outcomes. Results: The median follow up was 30 months (range, 4-68 months). The median survival time (MST), 1-year OS rate and 2-year OS rate of the whole group were 25 months, 51% and 39%, respectively. The average circulating lymphocyte counts declined during RT (1493.19 versus 503.48 cells/mu l, p < 0.001). A lower Min ALC was associated with worse OS (p = 0.001), with a cut-off value of 450 cells/mu l (sensitivity and specificity, 50% and 70.6%, respectively). The MSTs, 1-year OS rates and 2-year OS rates were 15 months versus 47 months, 27% versus 78% and 4% versus 71% for patients with relatively lower (<= 450 cells/mu l) and higher Min ALCs (>450 cells/mu l), respectively (p < 0.001). After adjusting for potential confounders, multivariate Cox regression analysis demonstrated that Min ALC independently predicted patients' OS (HR, 0.32; 95% CI, 0.15-0.69). Conclusions: Lower Min ALCs during RT may act as a worse prognostic factor for HCC after RT.