P12.44.A ADJUVANT CHEMORADIOTHERAPY WITH PROCARBAZINE, LOMUSTINE, AND VINCRISTINE (PCV) OR TEMOZOLOMIDE FOR 1P/19Q CO-DELETED ANAPLASTIC OLIGODENDROGLIOMA: A NETWORK META-ANALYSIS

Abstract BACKGROUND Anaplastic oligodendrogliomas (IDH-mutant and 1p/19q-codeleted) are rare diffuse gliomas characterized by favorable responses to chemoradiotherapy. Although radiotherapy (RT) combined with procarbazine, lomustine, and vincristine (PCV) has been the historical standard, temozolomide (TMZ) has been increasingly used due to its more favorable toxicity profile. However, direct comparisons between these regimens are limited. To compare the efficacy of RT combined with PCV versus RT combined with TMZ in adult patients with anaplastic oligodendroglioma characterized by confirmed 1p/19q co-deletion by conducting a network meta-analysis (NMA). MATERIAL AND METHODS A systematic search of PubMed, Embase, and the Cochrane Library was conducted up to March 2025. Eligible studies included patients with 1p/19q-codeleted anaplastic oligodendroglioma treated with RT+PCV, RT+TMZ, or RT alone. Both randomized trials, prospective, and retrospective cohorts were included. Studies comparing RT alone to RT+PCV or RT+TMZ were used to create indirect comparisons, with RT as a common comparator. A frequentist network meta-analysis with a random-effects model estimated hazard ratios (HRs) and 95% confidence intervals (CIs) for overall survival (OS) and progression-free survival (PFS). Consistency and heterogeneity were assessed using standard statistical methods. RESULTS Eight studies comprising 2,416 patients were included. In the network meta-analysis, compared with RT alone, RT+PCV significantly improved OS (HR: 0.617; 95% CI 0.465- 0.819; p = 0.0009), and PFS (HR: 0.547; 95% CI 0.415- 0.721; p < 0.0001), while RT+TMZ showed a trend toward improved OS (HR: 0.913; 95% CI 0.666- 1.252; p = 0.421) and PFS (HR: 1.270; 95% CI 0.870- 1.855; p = 0.215), without statistical significance. These comparisons with RT alone were included to establish the network structure. The primary objective of the study was the direct and indirect comparison between RT+PCV and RT+TMZ, in which RT+PCV demonstrated superior OS (HR: 0.676; 95% CI, 0.585-0.781; p < 0.0001) and better PFS (HR: 0.431; 95% CI, 0.325-0.570; p < 0.0001). Network consistency was confirmed (p > 0.1), (Q_between = 0.44; p = 0.506) to OS and (Q_between = 0.02; p = 0.8818) to PFS. CONCLUSION In patients with 1p/19q-codeleted anaplastic oligodendroglioma, RT combined with PCV provides superior survival outcomes compared to radiotherapy combined with TMZ. These findings support the continued use of PCV as the preferred chemoradiotherapy regimen when feasible, while emphasizing the need for future randomized trials to validate these results.