The effect of loose versus stranded seeds on biochemical no evidence of disease in patients with carcinoma of the prostate treated with iodine-125 brachytherapy

PURPOSE: The British Columbia Cancer Agency has been performing iodine-125 prostate brachytherapy since 1998, initially using loose seeds and phasing into the exclusive use of RAPIDStrand (RS) (Oncura Inc., Plymouth Meeting, PA) by November 2000. The aim of this study was to investigate rates of biochemical no evidence of disease (bNED) in patients treated with loose seeds compared with RS from this population-based cohort. METHODS AND MATERIALS: Between July 1998 and February 2006, 1500 implants were performed (327 loose and 1173 RS). Biochemical failure is reported using the Phoenix definition and prostate-specific antigen (PSA) >0.4 ng/mL at >= 48 months postimplant. Actuarial estimates were calculated by the Kaplan-Meier method. Analysis was repeated with the first 100 loose and stranded implants excluded to assess the learning curve effect. Log-rank test was used to evaluate differences in bNED. Variables showing association with bNED were included in a multivariate model. RESULTS: There was no difference between loose and stranded seeds. Estimated rate of bNED was 93.5% (95% confidence interval [CI], 90.6-96.4) at 7 years for patients treated with loose seeds and 94.0% (95% CI, 91.8-96.2) for patients treated with RS according to Phoenix definition (p = 0.846). Using the PSA >0.4 ng/mL definition, estimated rates were 91.3% (95% CI, 88.0-94.6) and 91.9% (95% CI, 89.7-94.1) for loose and stranded seeds, respectively (p = 0.871). Exclusion of the first 100 loose and stranded implants also revealed no difference in bNED. CONCLUSION: This study of 1500 patients treated with iodine-125 brachytherapy demonstrates no difference in bNED between loose and stranded seeds, using either Phoenix or PSA >0.4 ng/mL definitions of biochemical failure. Crown Copyright (C) 2011 Published by Elsevier Inc. All rights reserved.