Concurrent Chemoradiation and Adjuvant Chemotherapy in Newly Diagnosed Glioblastoma Multiforme: A Retrospective Analysis of Single Center

e14053 Background: The standard of care of glioblastoma multiforme (GBM) first line therapy is maximum safe debulking and posterior treatment based in concurrent chemo-radiation (Qt-Rt) followed by temozolomide-based chemotherapy. Despite a complete resection and adjuvant treatment, overall survival (OS) in patients (pts) with GBM is poor and it depends on tumor biology and patient characteristics. We analyzed retrospectively clinical and tumor biology characteristics of pts with GBM treated in our center with Qt-Rt +/- adjuvant Qt and their impact in OS. Methods: From November-2016 to October-2022, we collected data for 82 pts (median age: 60 years) who underwent Qt-Rt exclusively (25 patients) or Qt-Rt and adjuvant temozolomide (57 patients). Pts characteristics are detailed. Results: In multivariate analysis, significant difference of OS were observed in function of type of surgery (better OS in R0; p=0.015), performance status (better OS in PS 0-1; P=0.006), MGMT methylation (better OS in methylated; p=0.037), ATRX status (better OS in negative; p=0.05). No differences were founded in function of TERT (p=0.47) or p53 status (p=0.57). OS was significantly increased in pts treated with Qt-Rt and adjuvant Qt (17.7 +/- 1.7 months) vs Qt-Rt exclusively (11.35 +/-1.62 months) (p=0.013). After Qt-Rt treatment, radiological response was (%): no evidence of disease 13.4/partial response 6.1/stable disease 58.5/progressive disease 18.3/not evaluated 2.4. Most relevant adverse event G3/4 during Qt-Rt (%): thrombocytopenia 7.31, neutropenia 8, leukopenia 3.65, anemia 2.4, thrombosis 2.4. There were 2 toxic death (infection grade 5). After Qt-Rt, 57 pts received adjuvant treatment (median number of cycles: 5; range 1-15). Most relevant toxicity G3/4 during this therapy was (%): asthenia 3.05, anorexia 1.75, thrombocytopenia 5.26, neutropenia 3.05, leukopenia 1.75. There was 1 toxic death (infection G5). Pts that received 4 or more cycles of adjuvant temozolomide had a significant impact on OS versus those that completed 3 or less cycles (19.28 +/- 2 months vs. 12.05 +/- 1.5 months; p=0.022). Conclusions: Temozolomide-based chemotherapy in GBM is an effective and safe therapy and the premature interruption of this treatment may impact on OS. It is essential to know patient characteristics and tumor biology in order to identify patients that will beneficiate from this treatment.[Table: see text]