EXTERNAL BEAM IRRADIATION VERSUS 125-IODINE IMPLANT IN THE DEFINITIVE TREATMENT OF PROSTATE CARCINOMA

We reviewed the record of all 983 patients seen at the Hahnemann University, Department of Radiation Oncology for evaluation of prostate cancer during the megavoltage era. We compared the results of 276 patients who were treated definitively with either external beam irradiation or Iodine 125 implantation. The groups were similar in most prognostic characteristics. Where appropriate, multivariate statistical techniques were used to compensate for the effects of differences in grade and stage between the two groups. There were striking differences between implant and external beam patients in both local failure rates and disease-free survival, mostly attributable to poor local control in the implant patients. Thirty-eight percent of the Stage A and B implant patients failed locally in the first 5 years whereas only 5% of a comparable group of external beam patients did so. A2 patients, however, exhibited similar disease-free survival in both cohorts. Complication rates were 11% in the implant group and 19% in the external beam group. We conclude that there are serious doubts about the efficacy of Iodine 125 implantation in maintaining local control, and that this translates into worse relapse-free survival. By contrast, local control and relapse-free survival may be satisfactory in the A2 patients, and complication rates may be lower with implant. The above suggests that Iodine 125 interstitial implantation is well suited to only a minority of early stage prostate cancer patients and that most patients with Stage B and C prostatic carcinoma should be treated with either external beam irradiation or with radical prostatectomy.