(125)IODINE BRACHYTHERAPY FOR COLORECTAL ADENOCARCINOMA RECURRENT IN THE PELVIS AND PARAORTICS

Purpose: To evaluate the results of I-125 brachytherapy in colorectal cancers recurrent in the pelvis and paraortics. Methods and Materials: From September 1989 to January 1997, 29 patients with colorectal aden ocarcinoma recurrent in the pelvis or the paraortic nodes were treated intraoperatively with permanent (125)iodine seed implantation at the James Cancer Center of The Ohio State University (OSU). All patients h ad undergone prior surgery; 72% had prior EBRT. The implanted residual tumor volume was microscopic in 38% and gross in 62%. The implanted a rea (median 25 cc) received a median minimal peripheral dose of 140 Gy to total decay. An omental pedicle was used to minimize irradiation o f the bowel. Five patients received additional postimplant EBRT (20-50 Gy; median 30 Gy). Results: The 1-, 2-, and 1-year actuarial local-re gional control rates were 38%, 17%, and 17%, respectively, with a medi an time to local failure of 11 months (95% CI 10-12 months). The first manifestation of disease progression in 52% of the patients was local -regional. In addition, 22 patients (75%) developed distant metastases . The 1-, 2-, and 4-year actuarial overall survival rates were 70%, 35 %, and 21%, (median = 18 months; 95% CI: 14-22 months). Overall surviv al was better for patients smaller volume implants (p = 0.007), with a lower total activity implanted (p = 0.0003), with a smaller number of implanted sites (p = 0.004), and with microscopic residual disease (p = 0.01). Patients receiving additional EBRT also had a better prognos is (p = 0.005). Local tumor progression was the cause of death in 34% of the patients who have died at the time of this report and 56% died of distant metastases. Of the patients, 13 (45%) experienced lj toxic events, including 3 patients (10%) with enteric fistula. Neuropathy wa s not observed. Conclusions: I-125 brachytherapy can be successfully u sed for salvage in patients with recurrent colorectal cancer. Patients with isolated, microscopic, or minimal gross residual disease requiri ng small-volume implants and those receiving additional EBRT have a be tter prognosis. Postimplant EBRT is now routinely added, even for prev iously irradiated patients, in an attempt to improve local control. Co mpared to IOERT and IOHDR, I-125 brachytherapy is not associated with clinical neuropathy, probably due to the continuous low dose rate irra diation delivered by the I-125 seeds. (C) 1998 Elsevier Science Inc.