Intraoperative electron beam radiotherapy in the treatment of unresectable rectal cancer.

We treated 29 patients who had primarily unresectable rectal cancer with an aggressive combined surgical and radiotherapeutic approach. Each patient received 5,040 rad of preoperative external beam radiation therapy. Eighteen patients responded adequately to allow resection of all macroscopic tumor; 11 patients underwent resection but had residual cancer in the pelvis. A single bolus of 1,000 to 2,000 rad of intraoperative electron beam radiation was given. Follow-up time ranged from three to 66 months, with a median of 43 months for living patients. The actuarial local control rate at 36 months for the entire group was 87%. In the group of 18 patients who underwent resection, the local control rate was 92%, with a three-year survival rate of 70%. Our results are considerably improved over our prior experience without intraoperative radiation therapy--a 57% local control rate and a 30% three-year survival rate.