Loose seeds versus stranded seeds in I-125 prostate brachytherapy: differences in clinical outcome

Abstract

Purpose: To assess clinical outcome in terms of biochemical No evidence of disease (bNED) for patients with stranded seed implants versus loose seed implants in prostate brachytherapy.

Methods: From December 2000 until October 2006, we treated 896 T< or =2C Nx/0 Mx/0, prostate cancer patients with either stranded seed (n=538) or loose seed (n=358) I-125 implants. A total of 211 patients received a 6 months course of anti-androgen therapy, before treatment, for prostate volume reduction to <50 cc. Patients with very small and large gland volumes or a history of transurethral prostate resection, were preferably treated with stranded seeds, otherwise selection was arbitrary.

Results: The 5-year bNED rates (95% Confidence Interval) for stranded seed patients and loose seed patients were respectively 86% (82-90) and 90% (85-95), the total 5-year bNED rate was 87% (85-90). When adjusted for possible confounding factors in a Cox-regression analysis, type of seed was significantly associated with biochemical failure with a 43% risk reduction (hazard ratio: 0.57; 95% CI: 0.34-0.97) for loose seeds versus stranded seeds.

Conclusions: These results suggest that seed-type affects clinical outcome in prostate brachytherapy, with better bNED for patients with loose seed implants.