Predictors of survival and effect of short (40 Gy) or standard-course (60 Gy) irradiation plus concomitant temozolomide in elderly patients with glioblastoma: a multicenter retrospective study of AINO (Italian Association of Neuro-Oncology).

The efficacy of temozolomide (TMZ) plus radiation therapy (RT) in elderly patients with glioblastoma is unclear. We performed a large multicenter retrospective study to analyze prognostic factors and clinical outcome in these patients. Inclusion criteria were age ≥65 years, newly histologically confirmed glioblastoma, ECOG PS 0-2, adjuvant treatment with RT plus TMZ. We enrolled 237 patients; the average age was 71 and ECOG PS was 0-1 in 196 patients; gross total resection was performed in 174 cases. MGMT was analyzed in 151 persons and was methylated in 56 %. IDH1 was assessed in 100 patients and was mutated in 6 %. Seventy-one patients were treated with RT 40 Gy and 166 with RT 60 Gy. Progression-free survival and overall survival (OS) were 11.3 and 17.3 months, respectively. Overall survival was 19.4 vs 13.8 months for patients treated with RT 60 Gy and 40 Gy (p = 0.02); OS was 17.7 versus 16.1 months for patients treated with gross total resection vs partial surgery (p = 0.02); OS was 21.2 versus 13.6 months for methylated and unmethylated MGMT (p < 0.001). On multivariate analysis, gross total resection, RT 60 Gy, methylated MGMT and ECOG PS 0-1 were independent predictors of longer survival. Twenty-five patients (10 %) had grade 3-4 haematological toxicity during the concomitant treatment. We showed that, in elderly patients in good clinical condition treated with concomitant treatment, standard-course irradiation might be more effective than short-course irradiation. Methylated MGMT remains the most important prognostic factor.