IMCT-13LYMPHOPENIA IN ELDERLY PATIENTS WITH GLIOBLASTOMA TREATED WITH RADIATION AND TEMOZOLOMIDE

Abstract

BACKGROUND: Management of elderly patients with high grade glioma often includes radiation therapy (RT) +/- temozolomide (TMZ). A previous report showed that standard RT/TMZ resulted in severe lymphopenia in 40% of patients (median age of 57) with an associated shorter survival (Grossman, 2011). Similar findings were described in patients with head and neck, non-small cell lung, and pancreatic cancer. This study is designed to evaluate whether elderly patients (age ≥65) with glioblastoma (GBM) develop severe treatment related lymphopenia (TRL) after RT +/- TMZ and whether TRL is associated with reduced survival. METHODS: Elderly patients (age ≥65) newly diagnosed with GBM and followed-up at Washington University (2000-2013) were eligible. Radiation parameters and serial total lymphocyte counts (TLC) were collected. RESULTS: Seventy-seven patients were eligible: median KPS 70, median age 71 years (range 65 - 86) with 57% of patients >70 years, 52% female, 32% received RT <6 weeks, 42% had a baseline TLC <1000 cells/mm3 with 78% taking glucocorticoids. Baseline TLC prior to treatment was 1100 cells/mm3 with a fall by 45% at 2 months (median 600, range 100-2500). At 2 months, 22% of patients had a drop in TLC to <500 cells/mm3 (median 400, range 100-400). Patients with TLC <500 cells/mm3 at 2 months had a shorter survival than those with TLC ≥500 cells/mm3 with a median overall survival of 7.6 vs 10.1 months, respectively. Consistent with literature, an increased survival was found on multivariable analysis with MGMT methylation and gross total resection. We also found that higher baseline TLC was associated with increased survival. CONCLUSIONS: This is the first study to look at the development of TRL and its association with survival in elderly GBM patients. These findings add to the body of evidence that immunosuppression induced by chemoradiation is associated with inferior clinical outcomes.