Tolerance of brain to multiple courses of radiation therapy. I. Clinical experiences.

Patients with recurrent brain tumours years after initial radiation therapy pose a difficult management decision. Should retreatment be performed with irradiation, which carries a risk of necrosis, or should retreatment be with less effective agents but without unnecessary risks? We present the results of retreatment of 32 patients at the Mayo Clinic and the Joint Center for Radiation Therapy. Clinical improvement was seen in all retreated patients. The median survival was 36 months after completion of the second course of irradiation. Eight patients (25%) were alive, free of disease, from 22 to 315 months after retreatment. Of the 11 patients alive at the time of analysis, eight were experiencing productive lives and three were suffering from severe neurological damage. Evidence of brain necrosis was observed in two patients (6%); however, only 10/21 patients underwent autopsy examinations. Reirradiation of patients with late recurrences of brain tumours may offer neurological improvement and prolonged survival without excessive risk of necrosis.