3225 - Long-Term Bowel, Urinary, and Sexual Dysfunction Following Brachytherapy for Prostate Cancer with or without Rectal Spacer

12:45pm - 02:00pm PT

Hall F

Screen: 12

POSTER

Presenter(s)

Michael Folkert, MD, PhD - University of Washington Radiation Oncology, Seattle, WA

M. R. Folkert¹, R. Sato², J. B. Yu³, S. Bhattacharyya², E. Ezekekwu², and D. A. Hamstra⁴; ¹Fred Hutch Cancer Center, University of Washington Medical Center, Seattle, WA, ²Boston Scientific, Marlborough, MA, ³Department of Radiation Oncology and Applied Sciences, Dartmouth Geisel School of Medicine, Lebanon, NH, ⁴Department of Radiation Oncology, Dan L. Duncan Comprehensive Cancer Center, Baylor College of Medicine, Houston, TX

Purpose/Objective(s):

Rectal spacing has been shown to mitigate toxicity from external beam radiation therapy (EBRT) to treat prostate cancer (PCa) in clinical trials, with emerging evidence of similar benefit in brachytherapy (BT) monotherapy. However, real-world evidence on the long-term effectiveness of rectal spacers in BT is limited. This study assessed the long-term association between rectal spacing and diagnoses of bowel, urinary, and sexual dysfunction post BT using U.S. claims data.

Materials/Methods:

This retrospective study analyzed data from the Medicare 5% and 100% Standard Analytical Files, Merative™ MarketScan® Commercial Database, and Premier PINC AI™ Healthcare Database for PCa patients treated with BT monotherapy (2015-2021). Patients receiving combined BT and EBRT were excluded. Use of rectal spacer (polyethylene glycol spacer) was identified through Current Procedural Terminology (CPT®). Post-BT diagnoses of bowel, urinary, and sexual dysfunction were assessed. Cox proportional hazards regression was used for statistical comparisons, controlling for age, comorbidity, region, baseline bowel, urinary, or sexual dysfunction, a secondary diagnosis of colon, rectal, or bladder cancers, and BT modality (low dose rate [LDR] or high dose rate [HDR]) at a 0.05 significance level.

Results:

Among 13,858 patients found in the data, 1,198 (8.6%) patients received rectal spacers, while 12,660 (91.4%) did not. Patients with spacer were younger (67.5 yrs vs. 66.3, p<0.001), had less baseline bowel (1.4% vs. <1.0%, p=0.031) or urinary dysfunction (2.2% vs. 1.7%, p=0.002), and more likely to receive HDR (5.0% vs 9.3%, p<0.001) than patients without spacer. At a median 5-year follow-up, spacer use was associated with a lower incidence of bowel (6.1% vs. 10.2%, aHR 0.76 [0.59,0.97], p=0.027) and urinary dysfunction (34.2% vs. 26.3%; aHR: 0.84 [0.74,0.96], p=0.008). Sexual dysfunction was lower but insignificant among spacer users (6.7% vs 4.6%; HR: 0.79 [0.59,1.06], p=0.12). Subgroup analysis showed that spacer benefits were significant among LDR patients for bowel (HR 0.74 [0.57,0.96], p=0.021) and urinary dysfunction (HR 0.83 [0.72,0.94], p=0.005), with a consistent but insignificant association for sexual dysfunction (HR 0.75 [0.54,1.04]). However, no significant benefits were observed in HDR patients for bowel (HR 0.96 [0.45,2.04], p=0.91), urinary (HR 0.99 [0.68,1.43], p=0.94), or sexual dysfunction (HR 0.9 [0.47,1.7]).

Conclusion:

Based on post-BT diagnosis codes for bowel, urinary, and sexual dysfunction, rectal spacing as a standard of care intervention showed sustained significant benefit in reducing bowel and urinary dysfunction with a non-significant decrease in sexual dysfunction. Further investigation is crucial to comprehensively evaluate the long-term impact of rectal spacers in combination with BT on patient outcomes and healthcare costs.