Seed migration after transperineal interstitial prostate brachytherapy with I-125 free seeds: analysis of its incidence and risk factors.

<bold>Purpose: </bold>The purpose of this study was to evaluate the incidence and predictors of seed migration after transperineal interstitial prostate brachytherapy.<bold>Materials and Methods: </bold>From March 2007 to March 2011, 121 patients with stage T1-T2 prostate cancer underwent transperineal interstitial prostate brachytherapy. Pre-planning was performed 3 weeks prior to implantation, and the implants were inserted using the standard parallel needle insertion technique. All patients underwent a series of radiographs [chest radiography, kidney-ureter-bladder (KUB) radiography, and a CT scan] to assess whether seed migration had occurred on postoperative days 1 and 30, and 12 months.<bold>Results: </bold>Seed migration occurred in 31 (25.6 %) of 121 patients. A total of 51 of 7,883 (0.65 %) implanted seeds migrated. Migration was detected on postoperative day 1 in 16 patients, day 30 in 13 patients and at 12 months in 4 patients (migration occurred at different times in 2 patients). The migrated seeds were found in the lungs, pelvis, heart, mediastinum, kidney, inguinal canal, liver and sacrum. The number of needles was a statistically significant factor in seed migration.<bold>Conclusions: </bold>The seeds migrated to many organs. No decrease in the dose administered to the prostate or adverse effects associated with seed migration were noted. [ABSTRACT FROM AUTHOR]