Stereotactic Radiotherapy in Recurrent Glioblastoma: A Valid Salvage Treatment Option

Glioblastoma (GBM) is a dismal disease. Recurrence is inevitable despite initial surgery and postoperative temozolomide (TMZ) and radiotherapy. Salvage surgery is the standard treatment in selected patients. Chemotherapy, biological agents, and re-irradiation are other treatment approaches available. Stereotactic radiotherapy (SRT) is nowadays a common treatment as a salvage treatment option.

We reviewed the files of 132 GBM cases treated between 2010 and 2018. All patients received TMZ and radiotherapy after surgery or biopsy. Among the patients who had recurrence, we identified 42 cases treated with salvage SRT. The CyberKnife robotic system was used to administer SRT.

While the median follow-up time for all patients was 16 months (range 1-123), the median follow-up time for patients treated with SRT after initial diagnosis was 26.5 months (range 9-123). The median follow-up time after SRT was 10 months (range 2-107). SRT was performed in a median of 3 fractions (range 2-5). The median prescription dose was 20 Gy (range 18-30). While the median actuarial survival after initial diagnosis for patients treated with salvage SRT was 30 months (range 9-123), it was only 14 months (range 1-111) for patients who could not be treated with salvage SRT (p = 0.001). The median survival time after SRT was 12 months, and 1- and 2-year survival rates were 48 and 9%, respectively. The time to progression after SRT was 5 months (range 1-62), and 6-month and 1-year progression-free survival rates were 50 and 22%, respectively. Patients with longer time to recurrence >12 months had longer overall survival with respect to the ones having recurrence <12 months (p < 0.001). Salvage surgery had been performed in 7 out of 42 patients before SRT. These reoperated patients had significantly worse survival after SRT when compared to the patients who underwent SRT alone (p = 0.02). SRT was well tolerated and there was no grade III/IV toxicity.

SRT is a viable salvage treatment option for recurrent GBM. SRT provides acceptable local control and survival benefit for recurrent GBM cases. SRT can be considered especially in patients with long time to recurrence.