Chordoma: the results of megavoltage radiation therapy.

Twenty-four patients with chordoma who received one or more courses of megavoltage radiation therapy following biopsy or incomplete resection were reviewed. The uncorrected survival rate at five years was 62%, and at 10 years was 28%, but most patients had clinically detectable residual chordoma present at the time of death or last follow-up. The duration of symptomatic improvement following irradiation ranged from a few months to 18 years, median 3.5 years. Detailed dose-time and symptomatic response data for 56 patients from this series and from the literature who were treated by conventional daily fractionated megavoltage irradiation show no convincing evidence that symptomatic relief is more likely after high doses than after total doses of only 4000 to 5500 cGy. Patients are rarely cured of chordoma by partial tumor resection and conventional radiation. Four patients received multiple fractions of 100 cGy each day either as retreatment for recurrence, or as initial treatment. Symptomatic responses, and decreases in the size of tumor masses, were seen following total doses ranging from 2000 cGy/20 fractions/5 days/4 X 3 hourly fractions each day to 4000 cGy/40 fractions/12 days/4 X 3 hourly fractions each day. The short duration of follow-up in these patients prevents comparison with conventional fractionation. However, this technique presents one possible new approach for the treatment of chordoma.