Sequencing of Chemotherapy and Radiotherapy for Newly Diagnosed Anaplastic Oligodendroglioma and Oligoastrocytoma

Introduction: Adjuvant management of anaplastic oligodendrogliomas (AOs) and anaplastic oligoastrocytomas (AOAs) is guided by 2 seminal phase III trials, one of which utilized radiotherapy (RT) followed by chemotherapy (CT) (RT-CT), and the other in which CT was followed by RT (CT-RT). Both paradigms are endorsed by the National Comprehensive Cancer Network because no direct comparison in the first-line (nonprogressive) setting has been performed to date. This study of a contemporary national database sought to evaluate practice patterns and outcomes between both approaches. Materials and Methods: The National Cancer Database (NCDB) was queried for newly diagnosed AO/AOA treated with postoperative sequential CT-RT or RT-CT. Multivariable logistic regression ascertained factors independently associated with delivery of a particular paradigm. Overall survival (OS) between cohorts was compared using Kaplan-Meier methodology. Univariate and multivariate Cox proportional hazards modeling evaluated factors associated with OS. Results: Of 225 patients, 19 (8.4%) received CT-RT and 206 (91.6%) underwent RT-CT. Groups were well-balanced, although CT-RT was more often administered to men (P=0.009) and AOs (P=0.037). Median follow-up was 58 months. Median OS in the CT-RT cohort was 93 months (95% confidence interval, 37-150 mo), and 107 months (95% confidence interval, 72-142 mo) in the RT-CT group (P=0.709). Therapy sequence was not associated with OS on univariate (P=0.709) or multivariate (P=0.257) assessment. Conclusions: In the United States, most AO/AOA patients receiving sequential therapy undergo RT followed by CT. No differences in survival were observed with either approach; this addresses a knowledge gap and confirms that both paradigms are appropriate in the first-line setting.