RTHP-33. A SINGLE INSTITUTION RETROSPECTIVE ANALYSIS ON SURVIVAL BASED ON TREATMENT PARADIGMS FOR PATIENTS WITH ANAPLASTIC OLIGODENDROGLIOMA

Abstract

Anaplastic oligodendrogliomas are a type of high grade glioma defined molecularly by the 1p19q co-deletion. Currently, there is no curative therapy, and some studies have estimated median survival is estimated to be approximately 5 years. Current standard of care includes surgical resection followed by radiation and chemotherapy. However, the benefit of up-front radiation with chemotherapy compared to chemotherapy alone following surgical resection has not been shown in a randomized control trial. Given the long-term cognitive consequences of radiation therapy and the high percentage of patients who lives beyond 15 years with AO, there is an effort to balance longevity with radiation toxicity. As such we performed a retrospective single institution analysis of survival of patients with anaplastic oligodendroglioma over 20 years. 159 patients were identified as diagnosed with an anaplastic oligodendroglioma between 1996–2016. Of those, 57 patients were found to have anaplastic olidodendroglioma at original diagnosis and had long term follow-up. Sixty-six percent of patients were between the ages of 30–50 and mean KPS was 87.3. At the time of analysis, 33% of patients had died. In this cohort, 60% of patients were initially treated with radiation and chemotherapy (either temozolomide or CCNU) at diagnosis and 40% were treated with chemotherapy alone. Median overall survival for the entire cohort was 142 months. The related risk of progression in the upfront chemotherapy only group is approximately 5.87 times higher than the patients who received radiation and chemotherapy (Hazard ratio=5.87, 1.92–17.90, p=0.002). However, there was no significant difference in overall survival in patients treated with upfront chemotherapy compared to patients treated upfront with chemotherapy and radiation (p=0.14). On univariate analysis, there was no association between age, KPS, EOR, or upfront vs. delayed radiation and survival. As such initial treatment with chemotherapy alone may be an option for some patients with anaplastic oligodendroglioma.