P14.90 Survival outcomes and prognostic factors in glioblastoma patients treated with radiotherapy plus concomitant and adjuvant temozolomide - real-world study

Abstract

Abstract BACKGROUND Glioblastoma (GBM) is the most common and aggressive primary malignant brain tumour in adults. The current standard of care for newly diagnosed GBM is maximal surgical resection, followed by radiotherapy plus concomitant and adjuvant temozolomide (TMZ). This study aimed to evaluate the survival outcomes and identify predictors of survival among these patients. MATERIAL AND METHODS We performed a single-centre retrospective analysis of GBM patients treated with radiotherapy plus concomitant and adjuvant TMZ from 2013 to 2020. The analyses of progression-free survival (PFS) and overall survival (OS), each one evaluated starting from initial diagnosis, were performed. Survival curves were estimated with the Kaplan- Meier method and compared using the log-rank test. RESULTS Fifty-eight patients were identified. The median age was 61 years (range 18- 80), 51 (88%) patients were in ECOG-PS 0–1, 6 (10%) patients had isocitrate dehydrogenase (IDH) mutation and 53 (91%) of patients had undergone debulking surgery. At a median follow-up of 21 months, median OS was 12.8 months (95% confidence interval [CI] 9.7–15.9), whereas median PFS was 9.5 months (95% CI 8.5–10.5). The 1-year survival rate was 42% and the 2-year survival rate was 10%. Grade 3 or 4 hematologic toxicity occurred in 11 (19%) patients. Twenty-five (42%) patients completed at least 6 cycles of TMZ monotherapy with statistically significant differences between this sub-group and those who weren’t able to continue TMZ monotherapy [median OS 19.3 months (95% CI 14.4–24.2) vs 10.6 months (95% CI 7.8–13.4) p<0.001]. ECOG-PS = 0 [median OS 16.7 months (95% CI 13.4–20.0, p=0.001)] and patients under 65 years of age [median OS 15.6 months (95% CI 12.3–18.9, p=0.02) were associated with significantly better median OS. CONCLUSION The current standard of care treatment for GBM remains poor. An important factor predictor of survival is the completion of the 6 maintenance cycles of TMZ. At baseline, ECOG PS and the patient’s age could be used to define patient prognosis.