Genitourinary Toxicity In Prostate Cancer Patients With History Of Transurethral Resection Of The Prostate Undergoing High Dose Rate Brachytherapy With A Novel Urethral-Sparing Technique

Abstract

Prior transurethral resection of the prostate (TURP) is traditionally considered a contraindication to high dose rate prostate brachytherapy (HDR-B) due to increased risk of urinary morbidity and poor dose distribution in the prostate. We previously described a novel technique using a modified triple-lumen catheter to visualize and spare the TURP defect during CT-based HDR-B. We now report genitourinary (GU) toxicity in our institutional experience with this urethral-sparing technique. Prostate cancer patients with >3 months follow-up who underwent HDR-B using a modified triple-lumen catheter to visualize the TURP defect were included. Patient demographics, disease characteristics, dosimetry, and clinical outcomes were retrospectively reviewed. Toxicity was graded using NCI CTCAE v5.0 and classified as acute (≤90 days after HDR-B) or late (>90 days). Thirty-three patients met inclusion criteria. Median age was 76 years (IQR 74-80) and median follow up was 17.0 months (range 3.3-64.8). Thirty patients had 1 previous TURP and 3 patients had 2. Median time from most recent TURP to HDR-B was 49.0 months (IQR 6.1-125.8). Twenty-nine patients had newly diagnosed prostate cancer: 9 intermediate risk, 17 high risk, and 3 regional risk disease per NCCN. Among these, 1 patient received HDR-B monotherapy (27 Gy/2 fractions) and 28 received HDR-B boost (15 Gy/1 fraction) combined with external beam radiotherapy (EBRT). Four patients underwent salvage HDR-B for local recurrence 3-12 years after definitive radiotherapy: 1 received EBRT, 1 LDR-B and 2 HDR-B monotherapy. Among these, 2 patients received whole gland monotherapy (15 Gy/1 fraction, 36 Gy/6 fractions), 1 received partial gland monotherapy (27 Gy/2 fractions), and 1 received whole gland boost (18 Gy/3 fractions) combined with EBRT. Twenty-seven (82%) patients did not experience acute G2 or higher GU toxicity. Five (15%) patients experienced G2 toxicity (4 with retention or hematuria requiring temporary catheter placement and 1 with urinary frequency). One patient had G3 hematuria requiring procedural intervention 2 months after HDR-B. Only 2 of 29 newly diagnosed patients experienced acute G2 or higher GU toxicity, compared to 4 of 4 patients receiving salvage HDR-B re-irradiation. Twenty-seven (82%) patients did not experience late G2 or higher GU toxicity. Three (9%) patients experienced G2 hematuria (2 with clot retention requiring catheter placement and 1 requiring hyperbaric oxygen therapy) and 4 (12%) experienced G2 urinary incontinence. Two (6%) patients had late G3 toxicity (hematuria and retention) requiring procedural intervention. HDR-B in prostate cancer patients with a history of TURP has an acceptably low risk of G2 or higher GU toxicity when the urethral defect is adequately spared during CT-based planning. Acute G2 or higher GU toxicity occurred primarily in patients receiving salvage HDR-B re-irradiation and did not predict late G2 or higher GU toxicity.