Urinary morbidity with a modified peripheral loading technique of transperineal 125I prostate implantation

Abstract Purpose: Analysis of urinary morbidity within the first 12 months following a modified peripheral loading technique for permanent transperineal transrectal ultrasound (TRUS) guided 125 I prostate implantation and comparison of urinary morbidity with various clinical and implant parameters. Materials and Methods: Between October 1, 1996, and March 11, 1998, 87 patients with favorable, early stage prostate cancer were treated with permanent transperineal TRUS guided 125 I prostate implantation. A peripheral loading technique was utilized for source placement with 75–80% source distribution in the periphery and 20–25% source distribution centrally. A mean total activity of 38 mCi of 125 I was implanted (range, 19–66 mCi). The mean source activity was 0.43 mCi/source (range, 0.26–0.61 mCi/source) and the mean number of sources implanted was 88 (range, 56–134). The minimum prescribed dose to the prostate was 145 Gy. The median D 90 , V 100 , and V 150 were 152 Gy (range, 104–211 Gy), 92% (range, 71–99%), and 61% (range, 11–89%), respectively. The median follow-up time was 19 months (range, 12–29 months). Urinary morbidity was scored at 3 weeks and then at 3-month intervals for the first 2 years using a modified Radiation Therapy Oncology Group (RTOG) grading system (scale 0–5). Results: Most patients developed at least minor urinary symptoms with frequency or nocturia being the most common. Overall, 79% (69/87) of patients experienced urinary morbidity with 21% (18/87) reporting no symptoms. The incidence of overall Grade 1 urinary morbidity was 37% (32/87); Grade 2 morbidity was 37% (32/87); and Grade 3 morbidity was 6% (5/87). There was no Grade 4 or 5 morbidity. The incidence of Grade 0 frequency/nocturia was 36% (31/87); Grade 1 was 33% (29/87); Grade 2 was 30% (26/87); and Grade 3 was 1% (1/87). Grade 0 dysuria was seen in 56% (49/87) of patients; 32% (28/87) had Grade 1; 10% (9/87) Grade 2; and 1% (1/87) Grade 3 dysuria. Most urinary symptoms started a few weeks after implantation and began to subside by 6 months. At 12 months, 22% (19/87) of patients had persistent urinary symptoms (78% Grade 0, 15% Grade 1, 3% Grade 2, and 3% Grade 3). The mean urethral point dose was 174 Gy (range, 99–315 Gy). The mean number of sources implanted correlated significantly with the likelihood of developing acute urinary morbidity ( p = 0.03). The total activity implanted also correlated with the morbidity outcome dysuria ( p = 0.01) with a threshold seen at 37 mCi. Urethral point dose, source activity, intraoperative TRUS prostate volume, D 90 , V 100 , V 150 , patient age, pretreatment PSA, Gleason score, and T stage did not correlate with morbidity. Conclusions: Permanent transperineal TRUS guided 125 I prostate implantation using a modified peripheral loading technique is associated with mild urinary morbidity that resolves in 78% of patients by 12 months. Grade 3 urinary morbidity was encountered in only 6% (5/87) of patients. Urinary morbidity may be related to the total number of sources implanted and/or the total activity implanted. Overall urinary morbidity was not correlated with urethral point dose, source activity, intraoperative TRUS prostate volume, D 90 , V 100 , V 150 , patient age, pretreatment PSA, Gleason score, and T stage. The low incidence of urinary morbidity may be a consequence of our modified peripheral loading technique and/or the selection of patients with good-to-excellent preimplant urological parameters. Longer follow-up is necessary to assess biochemical control rates and long-term morbidity.