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MO_3_2529 - Impact of Corticosteroid Use During Chemoradiotherapy on Lymphopenia and Survival of Glioblastoma Patients

Monday, October 22
10:45 AM - 12:15 PM
Location: Innovation Hub, Exhibit Hall 3

Impact of Corticosteroid Use During Chemoradiotherapy on Lymphopenia and Survival of Glioblastoma Patients
C. Hui1, S. Rudra2, J. L. Campian3, D. Thotala4, D. E. Hallahan4, and J. Huang2; 1Saint Louis University School of Medicine, St. Louis, MO, 2Washington University School of Medicine, Department of Radiation Oncology, St. Louis, MO, 3Washington University in St. Louis, Department of Medical Oncology, St. Louis, MO, 4Washington University in St. Louis, Department of Radiation Oncology, St. Louis, MO

Purpose/Objective(s): Corticosteroids are commonly used to alleviate symptoms from cerebral vasogenic edema in patients with glioblastoma (GBM). Whether the use of corticosteroids during radiation therapy with concurrent temozolomide (CRT) can negatively influence acute severe lymphopenia (ASL) and overall survival (OS) in GBM patients remains controversial. Our study hypothesizes that increased average corticosteroid exposure during CRT increases risk of ASL and decreases OS of GBM patients.

Materials/Methods: We reviewed the records of 204 GBM patients treated with CRT from 2007 to 2016 at a single institution with available data to evaluate total lymphocyte counts (TLC) and dexamethasone use. The total dose of dexamethasone per day was recorded at baseline (prior to RT) and weeks 2, 4, and 6 during CRT. The average daily dexamethasone (ADD) dose over the 6-week period was calculated by dividing the estimated cumulative dexamethasone dose by 42 days. Patients were stratified into three ADD groups: <1 mg/day (low-dose), ≥1 mg/day but ≤ 4mg/day (intermediate-dose), and > 4 mg/day (high-dose). ASL was defined as TLC of <500 cells/µL within 3 months of starting RT. ASL rates and OS between the three groups were compared using Kaplan-Meier analysis. Multivariable analysis (MVA) was performed using logistic and Cox regression to identify independent predictors of ASL and OS, respectively.

Results: Of the 204 patients analyzed, 84 patients were in the low-dose group (median ADD: 0 mg/day, range: 0 – 0.67), 79 patients were in the intermediate-dose group (median: 2.67 mg/day, range: 1 - 4), and 41 patients were in the high-dose group (median: 6 mg/day , range: 4.33 – 17.33). Median ADD dose during CRT among all patients was 1.9 mg/day (0 - 17.3). ASL rates for the low-dose and intermediate-dose groups at 3 months were similar (19.3% vs 21.9%, respectively, P=0.27), while the high-dose group had significantly higher 3-month ASL rate of 67.1% than either the low-dose or intermediate-dose groups (both P<0.01). Median OS for the low-dose and intermediate-dose groups were similar (18.2 vs 19.2 months, respectively, P=0.96), while the high-dose group had significantly worse OS (median: 10.5 months) than the other 2 groups (both P=0.01). As a continuous variable, higher ADD dose was significantly associated with worse ASL and OS on MVA. However, when analyzed as a categorical variable, higher dose groups were not significantly associated with worse OS, and only the high-dose group was associated with worse ASL.

Conclusion: Although higher ADD use during CRT for GBM was associated with increased ASL rate and poorer OS, the adverse association appeared to be mostly limited to these patients who required relatively high ADD (> 4mg/day). Underlying tumor biology rather the true effect of corticosteroids may be causing the worse ASL and OS, and further investigation is warranted.

Author Disclosure: C. Hui: None. S. Rudra: None. J.L. Campian: None. D. Thotala: None. D.E. Hallahan: Stock; Cumberland Pharmaceuticals. Chairman; Washington University Department of Radiation Oncology. J. Huang: Speaker's Bureau; Viewray Inc. Travel Expenses; Viewray Inc.

Caressa Hui, BS

Washington University School of Medicine Department of Radiation Oncology

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