Treatment outcomes in 1p19q co-deleted/partially deleted gliomasa

Background: Radiotherapy with procarbazine, lomustine and vincristine improves overall-survival (OS) in patients with 1p19q co-deleted anaplastic oligodendroglioma/anaplastic oligoastrocytoma. Methods: This retrospective analysis investigated outcomes in patients with 1p19q co-deleted/partially-deleted oligodendroglioma, oligoastrocytoma, anaplastic oligodendroglioma or anaplastic oligoastrocytoma. Overall-survival and PFS were analyzed using the Kaplan-Meier method and prognostic factors using the Cox proportional hazard model. Results: 106 patients (Dec 97-Dec 13) were included. Median age was 40years (19-66), 58 were male (55%), ECOG-performance status (ECOG-PS) was 0 in 80 patients (75%). 1p19q status was co-deleted in 66 (62%), incompletely co-deleted in 27 (25%), 1p or 19q loss alone in 4 (4%) and 9 (8%) patients respectively. Isocitrate dehydrogenase-1 (IDH-1)-R132H mutation was found in 67 of 85 with sufficient material. Upfront treatment was given in 72 (68%) patients; temozolomide alone in 52 (49%). Median time to radiotherapy in 47 patients (44%) was 34.7 months and was 41.2 months in 9 patients with co-deleted/incompletely co-deleted anaplastic oligodendroglioma/anaplastic oligoastrocytoma who received upfront temozolomide alone. Median OS was not reached and 5 year OS was 91% for all groups (median follow-up 5.1years). On multivariable-analysis for all patients, receipt of therapy up-front versus none (P=0.04), PS 1 versus 0 (P<0.001) and 1p19q co-deletion/incomplete deletion versus 1p or 19q loss alone P=0.005) were prognostic for PFS. IDH-1 status was not prognostic for PFS. Conclusion: With similar survival patterns in low grade/anaplastic gliomas, molecular characteristics may be more important than histological grade. Longer follow-up/results of prospective trials are needed for definitive guidance on treatment of these patients