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MO_13_2805 - Evaluating Nationwide Practice Patterns in Chemoradiotherapeutic Regimens and Relative Efficacy of Chemoradiation Versus Adjuvant Radiation for Grade III Gliomas

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

Evaluating Nationwide Practice Patterns in Chemoradiotherapeutic Regimens and Relative Efficacy of Chemoradiation Versus Adjuvant Radiation for Grade III Gliomas
D. R. Smith1, C. C. Wu2, and T. J. C. Wang2; 1Columbia University College of Physicians & Surgeons, New York, NY, 2Department of Radiation Oncology, Columbia University Medical Center, New York, NY

Purpose/Objective(s): For newly diagnosed Grade III gliomas including anaplastic oligodendrogliomas (AO), anaplastic astrocytomas (AA) and anaplastic oligoastrocytomas (AOA), combined chemoradiotherapy (CRT) remains the current standard of care. Two landmark trials established multiagent (MA) chemoradiotherapy using PCV as first-line for 1p/19q-codeleted tumors. However, single-agent (SA) CRT using temozolomide is an alternative off-label option. Recently, interim analysis of CATNON confirmed that temozolomide-based SA-CRT offers significant survival benefit for 1p/19q-noncodeleted tumors. Here, we evaluated nationwide patterns in receipt of CRT and relative treatment efficacies for Grade III gliomas using the National Cancer Database (NCDB).

Materials/Methods: Patients with a first primary diagnosis of AO, AA or mixed glioma treated from 2006-2014 were identified from the NCDB. WHO Grade III glioma patients were identified whose initial treatment courses involved surgery with or without adjuvant RT (55-63 Gy in 25-34 fractions) or CRT. Factors examined included facility type, location, age, sex, race, Charlson-Deyo score, median income, insurance and extent of resection (EoR). Overall survival was assessed by Kaplan-Meier and Cox proportional hazards modeling. Potential predictors of MA- vs SA-CRT were examined using multivariate logistic regression. Adjusted survival comparison was performed using propensity score matching.

Results: From a total of 21877 AO, AA and mixed gliomas, 4553 WHO Grade III glioma patients were identified that met inclusion criteria. Median age was 47. Most patients (72.5%) received combined chemoradiotherapy, while a minority received only adjuvant RT (8.1%). At a median follow-up of 4.6 years, median survival was 88.3, 59.1 and 32.5 months for patients treated with chemoradiation, adjuvant RT or surgery alone, respectively (p<0.001), which remained significant on 1- and 3-month landmark analyses. On multivariate analysis, factors associated with improved survival included EoR, adjuvant RT and receipt of chemotherapy along with AO or mixed glioma histology, younger age, non-Medicare status, lower Charlson-Deyo score and higher median income. Among 3200 patients who received chemoradiation using known number of chemotherapeutic agents, 3088 (96.5%) received SA chemotherapy while only 112 (3.5%) received MA chemotherapy. Only EoR was associated with receipt of multi-agent chemotherapy (OR: 3.22 for STR vs. biopsy). Propensity score matched analysis detected no significant median survival difference between patients receiving SA vs. MA CRT (44.0 months vs. 53.6 months, p=0.36).

Conclusion: Independent of WHO Grade III histology, chemoradiation was associated with improved survival. Interestingly, despite only recent randomized data confirming its efficacy, SA-CRT was much more frequently offered than MA-CRT nationwide. Further study is needed regarding relative efficacy, particularly for 1p/19q-codeleted tumors.

Author Disclosure: D.R. Smith: None. C. Wu: None. T.J. Wang: Honoraria; Elekta, Wolthers Kluwer. Consultant; Abbvie, Merck, Doximity, Elekta. Advisory Board; American Cancer Society North Jersey, AstraZeneca. Travel Expenses; Abbvie, AstraZeneca, Elekta. Stock Options; Doximity.

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