Predictive factors of acute urinary morbidity after iodine-125 brachytherapy for localised prostate cancer: a phase 2 study

Purpose: To analyse predictive factors of acute urinary morbidity after transperineal permanent prostate brachytherapy. Methods and materials: Sixty patients treated in a phase 2 study with iodine-125 brachytherapy (9/1998 to 2/2000) for localised prostate adenocarcinoma were analysed after at least 1-year follow-up. Prescribed dose was 144 Gy and all patients had a pre-planning and a post-implant dosimetry. Urinary morbidity was evaluated prospectively using the Radiation Therapy Oncology Group (RTOG) scale. We examined the relationship between pre-implant ultrasound prostate volume, post-implant CT-scan prostate volume, neoadjuvant hormonotherapy, total number of needles and seeds, post-implant dosimetry variables, first 30 vs. last 30 treated patients and post-implant urinary morbidity. Results: All patients experienced some degree of urinary distress symptoms after treatment. Symptoms were generally mild grade 1 in 56% and grade 2 in 10% lasting less than 6 months. Eight patients (13%) required bladder catheter for acute urinary obstruction. At 1-year follow-up, nine patients (15%) complained from persistent dysuria requiring in three cases endoscopic prostate resection. The percentage of urethra volume receiving 216 Gy (cut-off 40%) and the pre-implant prostate volume (cut-off 31 ml) were the only statistically significant predictor of grade 2-3 or persistent urinary morbidity on multivariate analysis. Conclusion: Our short-term data suggest that both pre-implant prostate volume value and post-implant V.U. 150 value might be predictors for urinary morbidity after prostate brachytherapy