Iodine-125 implants versus external beam therapy for stages A2, B, and C prostate cancer.

From 1974 to 1984, 307 patients with local prostate cancer (Stage A2, B, or C) were referred to the Hunter Radiation Therapy Center, Yale-New Haven Hospital for definitive radiation therapy. One hundred forty-one patients underwent an interstitial Iodine-125 implant (IMP) and 166 patients received external beam irradiation (EB). For IMP patients with Stage A2, B, and C tumors, the actuarial 5-year disease-free survival (NED) rates were 88%, 84%, and 38% and the 9-year NED survival rates were 88%, 62%, and 30%, respectively. For EB patients with Stage A2, B, and C tumors, the 5-year NED survival rates were 88%, 77%, and 43% and the 9-year NED survival rates were 74%, 63%, and 37%, respectively. The NED survival rates by histologic grade were equivalent for the IMP and EB patients. The absolute local control rate (LCR) was 77% for all of the IMP patients but if one excludes patients who were inadequately treated, the LCR was 82%. LCR in the EB patients was 86%. The LCR for Stage A2, B, and C patients treated with EB was 100%, 94%, and 82%, respectively. The LCR for Stage A2, B, and C patients treated with an adequate IMP was 100%, 83%, and 71%, respectively. The complication rate was 8.5% in the IMP patients (with 0% severe complications) and 14% in the EB patients (with 3% severe complications). Our results indicate that a carefully selected group of IMP patients (Stage A2, B) will have an equivalent NED survival rate and an excellent LCR compared to EB patients but with fewer and less severe side effects.