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

PurposeTo 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.MethodsFrom December 2000 until October 2006, we treated 896 T⩽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.ResultsThe 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.ConclusionsThese results suggest that seed-type affects clinical outcome in prostate brachytherapy, with better bNED for patients with loose seed implants.