Gamma Knife Radiosurgery for Recurrent Glioblastoma Resistance to the Temozolomide

Purpose: The current standard of care for newly diagnosed glioblastoma is surgical resection to the extent feasible, followed by radiotherapy plus concomitant and adjuvant temozolomide. Ultimately despite this current standard treatment, almost all patients with glioblastoma will have relapse. Gamma knife stereotactic radiosurgery (GK-SRS) is a safe and less invasive treatment used as adjuvant therapy for patients with glioblastoma. Several studies have yielded conflicting results in the effectiveness of radiosurgery in glioblastoma. This article describes the results of our institutional experience with GK-SRS adjuvant therapy in the treatment of patients with recurrent glioblastoma resistance to the temozolomide. Method: Twenty-six patients with newly diagnosed glioblastoma were treated with operation and concomitant temozolomide radio-chemotherapy from 2006 to 2010. Eleven patients with recurrent glioblastoma were treated with GK. Seven patients were male and 4 were female. The median age at primary diagnosis of the tumor was 64.8 years (range, 51-81 yrs). All patients were received debulking surgery. Histology evaluations of all patients revealed glioblastoma. In all patients radiotherapy was performed as first-line therapy, applied as fractionated external beam radiotherapy with concomitant temozolomide chemotherapy. The median interval between initial diagnosis and primary GK was 9.0 months (range, 4-17 mos). The median target tumor size was 8.4 cm 3 (range, 0.65-38.8 cm 3 ). The median dose applied was 17.5 Gy (range, 15-20 Gy) prescribed to the 53.5% (range, 45-95%) isodose line that encompassed the target volume. The median follow-up time was 19.6 months (range, 11-48 months). Result: Median survival time of patients treated with GK was 21.0 months and without GK was 14.0 months. Treatment was well tolerated by all patients. Acute toxicities CTCAE Grade II occurred in one patient. Conclusion: Gamma knife radiosurgery is a relative safe and less invasive treatment and may play an important role in the treatment of recurrent glioblastoma resistance to the temozolomide.