CTNI-65. DETERMINANTS OF LONG-TERM SURVIVAL IN PATIENTS WITH IDH-MUTANT GLIOMAS

Abstract BACKGROUND Survival times of patients with IDH-mutant gliomas is variable and can extend to decades. Many studies only provide progression-free rather than overall survival times and prognostic factors remain ill-defined. Here we explored clinical disease characteristics of long-term survivors within a large cohort of patients with extended follow-up. METHODS This single-center, retrospective analysis included 114 patients with IDH-mutant glioma that either died due to tumor-related causes or survived at least 15 years after first diagnosis. Patient characteristics, outcomes, and prognostic factors were stratified by short- (< 15 years) versus long-term (≥ 15 years) survival. Initial diagnosis was (re-)classified according to the WHO 2016 classification. Uni- and multivariate analyses were performed. RESULTS Overall, 66 patients (58%) were diagnosed with astrocytoma and 48 patients (42%) with oligodendroglioma. Median follow-up of the survivors was 16.6 years (range 15-28.9). 62 tumor-related deaths (54%) had been reported at database closure. Patients that died before reaching 15 years survival time had been diagnosed with astrocytoma in 41 (72%) and oligodendroglioma in 16 cases (28%). The long-term survivor cohort comprised 25 patients (44%) with astrocytoma and 32 patients (56%) with oligodendroglioma. Long-term survival was associated with grade 2 histology (p < 0.01), smaller tumor volumes (p < 0.01), and lack of contrast enhancement (p = 0.02). 41 long-term survivors (72%) were initially monitored by a wait-and-scan strategy as opposed to 16 patients (28%) in the cohort of short-term survival (p<0.01). In patients with oligodendroglioma, a higher KPS was associated with longer survival (HR 0.25; 95% CI 0.02-0.67; p = 0.05). Tumor resection (HR 0.43; 95% CI 0.22-0.86; p = 0.02) and wait-and-scan strategies (HR 0.34; 95% CI 0.14-0.79; p = 0.01) were associated with longer survival in patients with astrocytoma. CONCLUSION Tumor resection followed by a wait-and-scan strategy may yield excellent survival times, especially in patients with IDH-mutant grade 2 astrocytoma. Age appears not be an important predictor for survival in patients with IDH-mutant gliomas.