PV QA 1 - Poster Viewing Q&A 1
Purpose/Objective(s): In this single institution retrospective study, we report acute and long-term genitourinary outcomes in patients with prostate cancer treated with a novel approach of combination single fraction HDR brachytherapy (15Gy x 1) and hypofractionated external beam radiation (EBRT) (2.5Gy x 16).
Materials/Methods: Patients treated with combination single-fraction HDR brachytherapy and hypofractionated EBRT between January 1st 2013 and January 31st 2014 were included. Patient characteristics including age, tumor stage, Prostate-Specific Antigen (PSA) at diagnosis, Gleason Score, International Prostate Symptom Score (IPSS) at consultation, and initial prostate volume were collected. Treatment data including use of androgen deprivation therapy (ADT), bladder neck D2cc, urethra D0.1 cc, and urethra D10% were collected. Acute toxicities were defined as those occurring within 90 days of initiating radiation treatment. Late toxicities were defined as those occurring after 90 days. Toxicities were graded using the Common Terminology Criteria for Adverse Events version 4.0 (CTCAE 4.0). Crude rates of acute GU toxicity and GU toxicity at last follow-up were calculated. The Kaplan Meier method was used to create survival curves, which were compared by the Log-Rank test.
Results: 53 patients were identified. Median follow-up was 50 months (range: 8 - 60). Median age was 66 years (range: 51-83). The percentage of patients in the National Comprehensive Cancer Network (NCCN) intermediate- and high-risk classes were 45% and 55%. Sixty percent of patients received ADT. HDR median bladder neck D2cc (%), urethra D0.1cc (%), and urethra D10% (%) were 49% (range: 35 - 67%), 95% (range: 83 - 103%), and 95% (range: 84 - 103%). Crude rates of acute GU toxicity grade 0, 1, and 2 were 11%, 40%, and 47%, respectively. No patient had grade 3 or greater acute GU toxicity. No acute urinary retention was noted. At the time of last follow-up, crude rates of late grade 0, 1, and 2 toxicity were 66%, 21%, and 9%, respectively. One patient (2%) had grade 3 toxicity. No patient developed urethral stricture. Late GU toxicity of any grade was significantly improved in patients with an initial IPSS of ≤ 15 or lower versus > 15 with a 3-year freedom from any toxicity rate of 92% [95% CI: 83%-100%] vs 80% [55%-100%], p = 0.016. Kaplan-Meier (KM) estimate of freedom from biochemical failure per Phoenix definition at 3 years was 96% (95% CI: 88-100%) and 79% (95% CI: 64-94%), in intermediate- and high-risk patients, respectively.
Conclusion: In this first report from a U.S. institution, patients undergoing single fraction HDR brachytherapy combined with hypofractionated external beam radiation have very low rates of long-term genitourinary toxicity and favorable early rates of PSA control.
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