[Value of radiosurgery in first-line therapy of glioblastoma multiforme. The Heidelberg experience and review of the literature]

Abstract

Aim: To describe the clinical results and the feasibility of a phase II dose escalation study of small boost target volumes with a radiosurgical technique in patients with positive early postoperative MRI scans.

Patients and method: Since 1986, 35 patients were treated within a concept for first line therapy. Including criteria were residual tumor < or = 5 cm and Karnofsky performance score > or = 70. The mean age was 54.5 years. The treatment concept included an operation for reduction of tumor volume and a postoperative irradiation. The postoperative irradiation was divided in 2 parts: first, a hyperfractionated (1.8 Gy single dose twice a day, 54 Gy total dose) irradiation was performed containing the tumor and the edema with a 2 cm safety margin. Secondly, a radiosurgical boost dose was delivered. The target volume of this radiosurgery was the contrast enhancing residual tumor in early postoperative MRI scans. The median boost dose was 15 Gy. Survival curves were calculated according to the Kaplan-Meier method. Quality of life was evaluated using objective criteria such as neurological findings, frequency of seizures and steroid medication.

Results: The median survival calculated from the time of diagnosis was 10.1 months. The 1- and 2-year survival rate were 35% and 6%, respectively. Young age tended to longer survival, patients younger than 53 years had a median survival of 10.4 months whereas patients older than 53 years showed a median survival of 9.2 months. The mean value of the boost volume was 22 cm3. Patients with smaller volumes had a median survival of 10.1 months and patients with bigger volumes showed a median survival of 9.9 months, 4.5 months after therapy, 75% of the patients showed improved or stable quality of life.

Conclusion: The feasibility of a radiosurgically delivered boost dose after postoperative irradiation could be demonstrated. The observed survival rate is comparable to the survival rates reported in the literature. Whether or not the radiosurgery after postoperative irradiation is able to prolong survival can only be evaluated in a randomized phase III trial.