Three different intraoperative radiation modalities (electron beam, high-dose-rate brachytherapy, and iodine-125 brachytherapy) in the adjuvant treatment of patients with recurrent colorectal adenocarcinoma.

Abstract

Intraoperative electron beam radiation therapy (IOERT) has been used in the treatment of patients with recurrent colorectal adenocarcinoma for the last 2 decades. Other intraoperative radiation modalities, such as intraoperative high-dose-rate brachytherapy (IOHDR) and intraoperative iodine-125 (125I) brachytherapy, present theoretic advantages for selected patients with recurrent colorectal adenocarcinoma. The experience of a single-institution series in which these three intraoperative radiation modalities were used in a nonrandomized manner is discussed in this report. Between September 1989 and January 1997, 80 patients with colorectal adenocarcinoma recurrent in the pelvis or in the paraaortic lymph nodes were treated with IOERT (28 patients), IOHDR (23 patients), or 125I brachytherapy (29 patients). The overall 5-year local control rate was 26% (median = 12 months; 95% confidence interval [95%CI], 6-17). Tumors in paraaortic sites had significantly better local control than those in the pelvis (P = 0.03). The 5-year overall survival rate was 4% (median = 20 months; 95% CI, 17-23). Patients with microscopic residual disease (P = 0.02) and those treated with postoperative external beam irradiation (EBRT) (P = 0.0007) had statistically significant longer survival. Forty-one percent of the treated patients experienced complications: These were severe (Radiation Therapy Oncology Group Grade 4-5) in 19% of patients. Intraoperative radiation can locally control recurrent colorectal adenocarcinoma in a select group of patients. Patients with localized relapses, microscopic residual tumor, and no distant metastases and those receiving additional EBRT are most likely to benefit from intraoperative irradiation. The authors now routinely recommend EBRT to all patients for whom it is suitable (including those who have had prior EBRT) and consider the combination of the intraoperative modalities whenever feasible.