RT-20 * DELAYING RADIOTHERAPY IN 1p19q CO-DELETED AND PARTIALLY DELETED GLIOMAS

Abstract

BACKGROUND: Radiotherapy with procarbazine, lomustine and vincristine improves overall survival (OS) in patients with 1p19q codeleted anaplastic oligodendroglioma (AOD)/anaplastic oligoastrocytoma (AOA). This retrospective study investigates outcomes with upfront temozolomide (TMZ) deferring radiotherapy in 1p19q codeleted/partially deleted AOD, AOA, oligodendroglioma (OD) or oligoastrocytoma (OA). METHODS: Patients with 1p19q codeleted/partially deleted AOD, AOA, OD and OA were analyzed for OS and progression-free survival (PFS) using Kaplan-Meier method. RESULTS: A total of 106 patients (Dec 97-Dec 13) were included. Median age was 40 years (19-66), 58 (55%) male, performance status (PS) 0 in 80 (75%) patients. 1p19q status; codeleted in 66 (62%), incompletely codeleted in 27 (25%), 1p or 19q loss alone in 4 (4%) and 9 (8%) patients respectively. Reason for presentation was seizures in 79 (75%), frontal lobe tumor location in 62 (58%) and contrast enhancement in 50 (47%). Upfront treatment was given in 72 (68%) patients; TMZ alone in 52 (49%) was well tolerated with med 12 cycles (1-24). Median time to radiotherapy in 47 patients (44%), 34.7mo. Median time to radiotherapy in AOD, AOA, OD, OA was 22.4mo, 1.4mo, 43.2mo and 43.4 mo respectively, given in median 3rd line of treatment (range 2-4), 41.2 mo (16.3-93.2) in 9 patients with codeleted/incompletely codeleted AOD who received upfront TMZ alone. Median OS was not reached for all groups (median follow up 5.1yrs). Median time to treatment for 36 patients with 1p19q codeleted/partially deleted AOD/AOA treated with TMZ alone upfront was 49.5 days (range 9-2248), median PFS was 46.3 months. On multivariable analysis, PS 1 vs 0 (Hazard ratio [HR]2.78, 95%confidence interval[CI] 1.57-4.93, p < 0.001) and 1p19q codeletion/incomplete deletion vs 1p or 19q loss alone (HR0.36, 95%CI 0.18-0.74, p = 0.005) were prognostic for PFS. Isocitrate dehydrogenase-1 status is pending. CONCLUSION: Delaying radiotherapy in 1p19q codeleted/incompletely deleted AOD/AOA may be a treatment option.