Megavoltage radiotherapy for aneurysmal bone cysts

Purpose: An aneurysmal bone cyst (ABC) is a rapidly expansile and destructive benign tumor of bone that is usually treated by curettage and bone graft, with or without adjuvant treatment. For recurrent tumors, or tumors for which surgery would result in significant functional morbidity, does radiotherapy (RT) provide a safe and effective alternative for local control? Patients and Methods: Nine patients with histologically diagnosed aneurysmal bone cysts without other associated benign or malignant tumors were treated at the University of Florida with megavoltage RT between February 1964 and June 1992. The patients received local radiotherapy doses between 20 and 60 Gy, with 6 patients receiving 26–30 Gy. In 6 patients the diagnosis was made by biopsy alone; 3 underwent intralesional curettage before RT. Minimum follow-up was 20 months; 7 of 9 patients (77%) had follow-up greater than 11 years. Results: No patient experienced a local recurrence (median follow-up, 17 years). One patient required stabilization of the cervical spine 10 months after RT because of dorsal kyphosis from vertebral body collapse. No other significant side effects were experienced, and no patients developed secondary malignancies. Four patients were lost to follow-up: at 20 months, 11.5 years, 17 years, and 20 years after the initiation of treatment, none with any evidence of local recurrence. All of the patients who had significant pain before RT had relief of their symptoms within 2 weeks of completion of therapy. Conclusions: Using modern-day RT, patients with recurrent or inoperable aneurysmal bone cysts can be treated effectively (with minimal toxicity) using a prescribed tumor dose of 26–30 Gy.