Results of a phase II trial of transrectal ultrasound-guided permanent radioactive implantation of the prostate for definitive management of localized adenocarcinoma of the prostate (radiation therapy oncology group 98-05)

Abstract

Purpose: To evaluate the effectiveness of transrectal ultrasound-guided permanent radioactive (125)I implantation of the prostate for organ-confined adenocarcinoma of the prostate compared with historical data of prostatectomy and external beam radiotherapy within a cooperative group setting.

Methods and materials: Patients accrued to this study had histologically confirmed, locally confined, adenocarcinoma of the prostate with clinical Stage T1b, T1c, or T2a, no nodal or metastatic disease, prostate-specific antigen level of < or =10 ng/mL, and Gleason score of < or =6. All patients underwent transrectal ultrasound-guided radioactive (125)I permanent seed implantation into the prostate. The prescribed dose was 145 Gy to the prostate planning target volume.

Results: A total of 27 institutions accrued a total of 101 patients to this protocol, with no institution accruing >8 patients. Six patients were ineligible, leaving 95 properly entered as eligible in the study. The median follow-up was 5.3 years (range, 0.4-6.5 years). At 5 years, 5 patients had local failure, 1 had evidence of distant failure, and 6 (6%) had biochemical failure. The overall survival rate at 5 years was 96.7%. At last follow-up, no patient had died of prostate cancer or related toxicities. Eight patients had a maximal acute toxicity level of 3, and no patient had Grade 4 or 5 acute toxicity. During follow-up, 2 patients had maximal Grade 3 toxicity, both related to bladder issues, and no patient experienced Grade 4 or 5 toxicity.

Conclusion: The results of this clinical protocol (a multi-institutional trial of brachytherapy for localized adenocarcinoma of the prostate) have demonstrated that this type of trial can be successfully completed through the Radiation Therapy Oncology Group. Biochemical disease-free survival was comparable with other brachytherapy published series and with the results after surgery and external beam radiotherapy.