Radiotherapy with concomitant and adjuvant temozolomide (six cycles) is the standard treatment after surgery in glioblastoma patients. Few studies have assessed the impact of additional cycles of temozolomide on survival.

We conducted a bi-centric retrospective study comparing survival and toxicity according to the number of cycles of adjuvant temozolomide.

Fifty-eight patients were included. All patients received radiotherapy with concomitant temozolomide. Thirty-eight patients received six cycles, while 20 received nine or more (median=14) cycles. The risk of recurrence was significantly higher in the group receiving six cycles compared to the other group. Prolonged treatment improved progression-free survival (p=0.03) and overall survival (p=0.01) in multivariate analysis without a significant increase in toxicity.

Prolonged administration of temozolomide seems to improve progression-free and overall survival, without increased toxicity. Prospective studies in larger populations are needed to better-define the population to whom it can be proposed and its optimal duration.