NCMP-12. PREVALENCE OF RADIONECROSIS IN RECURRENT GLIOBLASTOMA

Abstract

Abstract INTRODUCTION Glioblastoma (GBM) standard treatment consists of maximum and safe surgical resection, followed by radiation therapy in combination with temozolomide. Some patients show radiological and/or clinical deterioration soon after radiotherapy treatment. Early MRI changes, in the first 3 months following radiation is considered pseudo-progression. After this initial period, changes are considered as tumor recurrence. However, cases of early radiological deterioration have been related to radionecrosis. When tumor progression is suspected on imaging, it may causes treatment withdrawal or change. Therefore, for a certain percentage of patients, effective treatment could be abandoned in the presence of radionecrosis. METHODS The aim of the study is to assess the prevalence of radionecrosis at the Hôpital de l'Enfant-Jésus. This is a retrospective, observational case-control study evaluating recurrent GBM patients who underwent a second resection surgery. RESULTS The charts of 110 GBM patients with second resection were retrospectively reviewed (men: 62%, mean age: 58.3 years). Among these patients, we observed 87 cases of GBM recurrence as compared to 23 cases of radionecrosis (21%). No statistically significant difference was observed between the two groups regarding demographics, survival, Karnofsky performance status, type of surgery and treatments received. However, in the radionecrosis group, decreases in time between the 2 surgeries (55.3 vs. 24.3 weeks, p = 0.006) and in the number of cycles of chemotherapy received (5.7 vs. 3.7 weeks, p = 0.004) were observed as compared to GBM group. CONCLUSIONS This study characterizes demographically the patients with second surgery for suspicion of GBM in order to better adapt the treatments. Clinical and radiological data could not differentiate radionecrosis from true tumor recurrence or progression. A prospective study will be carried out as a second step, in order to determine radiological or molecular factors that could predict the presence of radionecrosis.