Concurrent Versus Sequential Chemoradiation for Low-grade Gliomas Meeting RTOG 9802 Criteria.

Purpose: Radiation Therapy Oncology Group (RTOG) 9802 has established postoperative radiation therapy (RT) and chemotherapy sequentially as the new standard of care for patients with high-risk low-grade glioma (LGG) meeting trial criteria. Although this trial investigated sequential chemoradiation therapy (sCRT) with RT followed by chemotherapy, it is unknown whether concurrent chemoradiation therapy (cCRT) may offer advantages over sCRT. Materials and Methods: The National Cancer Database (NCDB) was queried for newly diagnosed World Health Organization (WHO) grade II glioma. Patients with unknown surgery, RT, or chemotherapy status were excluded, along with patients below 40 years old who underwent gross total resection to coincide with RTOG 9802 exclusion criteria. The chi(2), the Fisher exact, or Wilcoxon rank-sum tests evaluated differences in characteristics between groups. Kaplan-Meier analysis was used to evaluate overall survival (OS) between groups (sCRT vs. cCRT). Cox proportional hazards modeling determined variables associated with OS. Results: In total, 496 patients were analyzed (n=416 [83.9%] cCRT, n=80 [16.1%] sCRT). Sequencing or concurrency of therapy did not independently influence survival on univariable/multivariable analysis. Factors associated with worse OS on multivariable analysis included advanced age (P<0.001), whereas mixed glioma (P=0.017) and oligodendroglioma (P=0.005) were associated with better OS than astrocytoma histologies. Conclusions: This is the only analysis of which we are aware of cCRT versus sCRT for LGG. There is no evidence that cCRT improves outcomes over sCRT.