Control of unresectable recurrent anorectal cancer with gold-198 seed implantation

Gold-198 seed implantation was performed in 18 patients with 19 sites of unresectable anorectal cancer. The seeds were placed under computed tomography guidance in the region of the sciatic notch in 14 patients (78%); one patient had two implants performed. Unresectable disease in the presacral region was implanted at laparotomy in two patients. Mean dose delivered was 10,791 cGy (range, 4376 to 22,000 cGy) to an average volume of 29 cm³ (range, 5.1 to 84.77 cm³). Median length of follow-up after implant was four months; eight patients (44%) were monitored for three months or less, and five patients (28%) were monitored for at least six months. Stabilization/regression of disease and symptoms in the implanted volume was accomplished in 17 (94%) of 18 patients. At last follow-up, three patients (17%) had no evidence of disease and three patients had stable disease in the pelvis, totaling 34% local control of pelvic disease. A total of 12 patients (66%) had progression of pelvic disease. Morbidity, as a result of the procedure or radiation dose, was limited. Gold-198 seed implantation accomplished stabilization of recurrent anorectal cancer and its symptoms without severe morbidity. Uncontrolled locoregional disease in the pelvis outside the implant volume is the primary cause of disease progress.