ACTR-72. IDH-WILD TYPE GRADE II GLIOMAS: A RETROSPECTIVE SERIES OF ITALIAN ASSOCIATION OF NEURO-ONCOLOGY

Abstract

BACKGROUND: Information regarding clinical characteristics and response to treatments of IDH-wild type grade II gliomas are still lacking. MATERIAL AND METHODS: We performed a retrospective study on patients with WHO grade II IDH wild type gliomas recruited from 1999 to 2017 in six Italian Institutions. IDH mutation was assessed by either immunohistochemistry or sequencing (in case of negative immunohistochemistry). Exclusion criteria were the presence of minimal anaplastic foci or radiological features of HGGs. Kaplan-Meier curves and Cox-regression models were used for univariate and multivariable analysis. RESULTS: Out of 194 patients 122 met the inclusion criteria. Median age was 45 years. Non-enhancing tumours on MRI accounted for 74% while 26% had mild contrast enhancement. Surgery consisted in gross total resection in 29%, partial/subtotal in 45%, biopsy in 24%, and unknown in 2%. According to WHO 2007 astrocytomas were 44%, oligodendrogliomas 35%, and oligoastrocyomas 21%. Post-surgical management consisted in observation with MRI in 42%, chemoradiation in 21%, chemotherapy alone in 21%, radiotherapy alone in 5%, radiotherapy followed by chemotherapy in 5%, and 6% unknown. Median time of followup was 31 months. Median PFS at first recurrence from diagnosis was 24.0 months (1.2 147.0). Treatments at recurrence consisted in second line chemotherapy in 33 cases (42.3%), second surgery in 18 cases (23.1%), radiotherapy in 10 cases (10.4%), and palliative care in 13 cases (16.7%). Median OS was 45.3 months (1.0 225.6). Factors associated with longer PFS and OS in univariate analysis were younger age, absence of contrast enhancement, and gross total resection. Younger age and gross total resection retained the statistical significance in multivariable analysis. CONCLUSIONS: WHO grade II IDH-wild type gliomas have a worse outcome as compared with IDH-mutant tumours. This is the first real life study reporting that gross total resection improves the outcome.