ATIM-35. THE ASSOCIATIONS BETWEEN TOTAL LYMPHOCYTE COUNTS AFTER CONCOMITANT CHEMORADIATION WITH OVERALL SURVIVAL IN PATIENTS WITH NEWLY DIAGNOSED GLIOBLASTOMA

Several studies have been conducted to determine the relationship between post-treatment total lymphocyte count (TLC) and overall survival (OS) in patients with malignant tumors including glioblastomas (GBMs). In this retrospective study, whether patients with newly diagnosed GBM experience significant lymphopenia after concomitant chemoradiation (CCRT) was evaluated, and whether TLC after this treatment is associated with OS in the treated population was examined. Using electronic medical records, all patients newly diagnosed with GBM between 2008 and 2016 at Seoul St. Mary’s Hospital were retrospectively examined. The eligible criteria included the following: 1) craniotomy with surgical resection or biopsy, 2) completion of CCRT, 3) accessible baseline and/or follow-up complete blood count (CBC). Median TLC significantly decreased after completion of CCRT, compared to TLC at baseline (1,742 versus 1,319 cells/mm3, P-value < 0.001). Patients with TLC < 1,200 cells/mm3 at 4 weeks after the completion of CCRT showed shorter survival than those with TLC ≥ 1,200 cells/mm3 with median OS of 14.5 versus 21.0 months (P-value = 0.017). Also, in multivariate analysis for OS, TLC < 1,200 cells/mm3 at 4 weeks after the completion of CCRT (HR 1.97, 95% CI 1.61 – 2.25, P-value = 0.004) were significantly associated with shorter survival. The results from the present study indicate that treatment-related total lymphocyte counts after CCRT is associated with worse survival in patients with newly diagnosed GBM.