OBJECTIVE: To explore an association with survival of modifying the current standard of care for patients with newly diagnosed glioblastoma of surgery followed by radiotherapy plus concurrent and 6 cycles of maintenance temozolomide chemotherapy (TMZ/RT → TMZ) by extending TMZ beyond 6 cycles.
METHODS: The German Glioma Network cohort was screened for patients with newly diagnosed glioblastoma who received TMZ/RT → TMZ and completed ≥6 cycles of maintenance chemotherapy without progression. Associations of clinical patient characteristics, molecular markers, and residual tumor determined by magnetic resonance imaging after 6 cycles of TMZ with progression-free survival (PFS) and overall survival (OS) were analyzed with the log-rank test. Multivariate analyses using the Cox proportional hazards model were performed to assess associations of prolonged TMZ use with outcome.
RESULTS: Sixty-one of 142 identified patients received at least 7 maintenance TMZ cycles (median 11, range 7-20). Patients with extended maintenance TMZ treatment had better PFS (20.5 months, 95% confidence interval [CI] 17.7-23.3, vs 17.2 months, 95% CI 10.2-24.2,= 0.035) but not OS (32.6 months, 95% CI 28.9-36.4, vs 33.2 months, 95% CI 25.3-41.0,= 0.126). However, there was no significant association of prolonged TMZ chemotherapy with PFS (hazard ratio [HR] = 0.8, 95% CI 0.4-1.6,= 0.559) or OS (HR = 1.6, 95% CI 0.8-3.3,= 0.218) adjusted for age, extent of resection, Karnofsky performance score, presence of residual tumor, O-methylguanine DNA methyltransferasepromoter methylation status, or isocitrate dehydrogenase () mutation status. p p p p (MGMT) IDH6
CONCLUSION: These data may not support the practice of prolonging maintenance TMZ chemotherapy beyond 6 cycles.
CLASSIFICATION OF EVIDENCE: This study provides Class III evidence that in patients with newly diagnosed glioblastoma, prolonged TMZ chemotherapy does not significantly increase PFS or OS.
