Prior transurethral resection (TUR) of the prostate reduces post-operative urinary morbidity associated with transperineal interstitial permanent prostate brachytherapy (PB)

Abstract

Purpose: Early prostate brachytherapy (PB) techniques used uniform source loading patterns that delivered an excessive urethral dose, resulting in high rates of necrosis, urinary retention and incontinence if performed following TUR. Although many aspects of dosimetry, imaging and intraoperative technique has evolved, prior TUR is still frequently cited as a contraindication to PB based on the earlier adverse experience. We reviewed our experience with PB following TUR to assess both urinary morbidity and prostatic dose coverage using more contemporary techniques. Materials and Methods: 300 consecutive patients undergoing PB as primary treatment for T1-T2 prostate cancer from 9/98-1/01 were followed prospectively. All were treated by the same two physicians and physicist using a modified peripheral loading technique and pre-plan dosimetry. Treatments included PB alone (Pd-103 or I-125) or with 45 Gy EBT boost, with selected patients receiving androgen ablation (AA). PB was performed using a B&K Leopard ultrasound with placement of pre-loaded needles on transverse imaging, and source deposition on longitudinal imaging. Dosimetric coverage was evaluated using an in-house treatment planning system which included CT-based dose-volume histogram analysis approximately 3-4 weeks post implant. Data analysis included details of the implant and dosimetry, size of TUR defect, number of sources retrieved at cystoscopy after PB, V100, V80, and urinary retention (defined as any need for a catheter after post-op day 1. Results: 33 of 300 (11%) had undergone prior TUR 0.25-24 years before PB. Follow-up ranges from 3-33 months. TUR defects were noted in 23 on pre-implant planning ultrasonography. Other than older age (60-84, m=75 vs. 42-84, m=66) and less urinary retention after PB (3% vs. 22%), prior TUR patients were well matched to those with no prior TUR for Gleason Score, PSA, target volume, gland size, I-PSS, numbers of needles and sources, and treatment delivered. Specific treatments in the prior TUR group included implant alone in 19, while 14 received 45 Gy EBT boost (8 prior to implant, 6 after implant); 12 received I-125, 21 received Pd-103, and 18 received AA. Sources were retrieved at cystoscopy immediately after implant in 10 patients (30.3%). This included a single source in 7 patients, 4 sources in 2 patients, and 5 sources in a single patient. V100 ranged 93.6-100% (m=98.1%) and there was no underdosage (defined as any volume < 80% prescribed dose) identified around the TUR defect or elsewhere in the prostate. There were no cases of urethral necrosis and none are incontinent. Conclusion: Using contemporary techniques of PB including a modified peripheral loading pattern, bi-planar imaging, and pre-loaded needles, prior TUR should not be a contraindication to PB. In fact, our experience suggests that patients who have previously undergone TUR may tolerate PB even better in terms of reduced urinary retention. This more contemporary philosophy allows for the inclusion of many patients previously thought not to be candidates for PB. Planned TUR for relief of voiding symptoms in selected patients prior to PB should now be evaluated.