Combined interstitial iridium-192 implant and external beam irradiation in the treatment of carcinoma of the prostate

Purpose: to assess the impact of local tumor control on ultimate disease free survival. Materials and methods: 450 patients with biopsy proven adenocarcinoma of prostate, stage A2 to C, were treated from February 1980 to December 1991. 65% of patients had B2-C disease. All patients underwent staging bilateral retroperitoneal pelvic lymph node dissection and transperineal afterloading Iridium-192 implant to prostate, delivering minimum tumor dose of 30 to 40 Gy over 40 to 60 hours. In addition, all patients with stage B and C disease also received external megavoltage radiation to prostate to doses of 30 to 36 Gy over (31(2)) to 4 weeks. Results: Local tumor control was defined by combination of at least two of the following parameters: i) normal DRE, ii) normal serum PSA, iii) normal TRUS exam, and iv) negative re-biopsy at least 18 months post treatment. (416(450)) (92%) of patients achieved local tumor control with minimum follow-up of 2 years to maximum follow-up of 14 years (median 8 years). 33 of 111 (30%) patients had positive re-biopsy. Total 78 (17%) patients developed metastases. Metastatic rate was 58% for patients with positive re-biopsy compared to only 6% for patients who had negative re-biopsy (p=0.0001). Overall and disease free survivals for the entire group at 5 and 10 years are 86%, 86%, 70% and 76%, respectively. This has been well correlated with stage and histologic grade as well as status of pelvic lymph nodes. Treatment related moderate to severe complications such as cystourethritis, proctitis, rectal ulcerations, incontinence or urethral stricture formation, etc. has occurred in less than 6% of cases, especially in the initial developmental phase of this treatment protocol. Conclusion: 1) combination of interstitial Iridium-192 implant and external beam irradiation in the treatment of carcinoma of the prostate is safe and efficacious (92% local control and 76% disease free survival at 10 years). 2) improved local tumor control ultimately results in increased disease free survival. 3) positive re-biopsy post treatment appears to have significant prognostic value