2376 - Patient-Reported Outcomes (PROs) in Prostate Cancer Patients Undergoing IMRT vs. IMRT with Brachytherapy

Purpose/Objective(s): For patients with high-risk prostate cancer, the ASCENDE-RT trial showed that adding brachytherapy (BT) to intensity modulated radiation therapy (IMRT) improves cancer control over IMRT alone but significantly increases toxicity. However, real-time brachytherapy (compared to pre-planning as was done in ASCENDE-RT) may better spare organs at risk and thereby decrease toxicity. We compare prospectively collected PROs of consecutive patients treated at our institution.

Materials/Methods: As part of our clinical workflow, the International Prostate Symptom Score (IPSS) and Expanded Prostate Cancer Index Composite-Clinical Practice (EPIC-CP) are collected at pre-treatment and then prospectively for all patients. We analyzed patients treated from 2021-2024, and compared outcomes between patients treated with IMRT vs IMRT/BT at 0-6, 6-12, and 12-24 months. Minimally important differences (MID) were defined based on published literature as a change of 3 points for IPSS and 1 point for EPIC-CP. Statistical tests were performed using SAS v9.4.

Results: 112 patients were analyzed (IMRT: n=50; IMRT/BT: n=62), median age 67. Both groups significantly increased IPSS from baseline to 0-6 months (+5.0 vs +7.0, NS). IMRT group returned to baseline for IPSS, whereas IMRT/BT group had persistently elevated symptoms at 6-12 months (-1.0 vs + 1.0, p = 0.02) and 12-24 months (+0.0 vs + 3.0, p = 0.18). The EPIC-CP measure showed similar findings, with urinary QOL for IMRT patients recovering to baseline, while IMRT/BT patients had persistently elevated urinary incontinence (0.0 vs +1.0, p=0.05) and urinary irritation (0.0 vs +1.0, p=0.02) at 12-24 months. However, only a subset of the IMRT/BT group had elevated symptoms meeting the MID in IPSS (26%), EPIC-CP urinary irritation (21%), and urinary incontinence (18%). Bowel function remained stable across groups.

On multivariable analysis that adjusted for race, baseline IPSS, and use of pelvic radiation, IMRT/BT was associated with higher odds of increasing urinary incontinence that met the MID threshold (OR=18.79, p=0.02). There was no difference between IMRT and IMRT/BT patients in IPSS or urinary irritation.

Conclusion: Both IMRT alone and IMRT/BT result in post-treatment QOL declines. IMRT patients recovered by 6-12 months, whereas IMRT/BT patients had mild but persistent urinary QOL declines at 12-24 months, with 1-2 points increases compared to baseline. These data inform patient decision-making balancing the disease control benefit vs mild increased urinary symptoms from adding BT.

Abstract 2376 - Table 1: Median IPSS and EPIC-CP scores (higher score = worse symptoms)