3227 - A Prospective Cohort Study Assessing Patient Reported Outcomes after Post-Prostatectomy Radiation Therapy: Longer-Term Follow-Up through 5 Years

C. Lynch¹, G. Rajeev-Kumar², Y. Che³, and S. Liauw⁴; ¹Northwestern University Feinberg School of Medicine, Chicago, IL, ²University of Chicago, Chicago, IL, ³University of Chicago Department of Public Health Sciences, Chicago, IL, ⁴Department of Radiation and Cellular Oncology, University of Chicago, Chicago, IL

Purpose/Objective(s): Salvage radiotherapy (RT) after prostatectomy is common, but data for long term patient-reported outcomes (PROs) are limited. We report on the largest cohort to date assessing quality of life (QOL) outcomes with 5 years of median follow-up. Materials/

Methods: PROs for men undergoing salvage intensity modulated RT following post-prostatectomy biochemical failure at a single institution were prospectively collected using the Expanded Prostate Cancer Index Composite (EPIC-26). Declines in QOL were deemed significant if they exceeded the minimally important difference (MID), defined as 7.5, 6, 5, and 11 for the urinary incontinence (UI), urinary obstruction/irritation (UO), bowel function (BF), and sexual function (SF) domains, respectively. Physician-reported genitourinary (GU) and gastrointestinal (GI) toxicities were recorded prospectively with CTCAE v3.0. Univariable and multivariable (MVA) general estimating equation and Fine-Gray models assessed the association between clinical factors and QOL or adverse events.
Results: Between 2007 and 2019, 317 men were treated to a median dose of 68.4 Gy to the prostate bed with 72% receiving a median dose of 50.4 Gy to the pelvic nodes and 72% receiving hormone therapy. Median follow-up was 64 months. Table 1 shows median QOL scores over time. At 5 years, rates of QOL decline exceeding MID for UI, UO, BF, and SF were 32%, 27%, 30%, and 17%, respectively. Of men whose QOL decline exceeded MID, 35%, 49%, 54%, and 40% had subsequent improvement in UI, UO, BF, and SF scores, respectively, and no longer exceeded MID at last follow-up. The cumulative incidences of grade 2+ GU and GI toxicity at 5 years were 30% and 7%, respectively. Incontinence was the most common GU toxicity (26%). Rates of grade 3+ GU and GI toxicity were 5% and 2%, respectively. Of men experiencing grade 2+ GU toxicity, 40% recovered at last follow-up. On MVA, race, hormone therapy duration, age, and volume of bladder or rectum receiving 65-75 Gy were significantly associated with change in EPIC UI, UO, BF, and SF domain scores. Rectal volume receiving 75 Gy, RT prescription dose, and anticoagulation use were significantly associated with grade 2+ GU and GI toxicity.
Conclusion: Post-prostatectomy RT was well-tolerated through 5 years. Of patients experiencing QOL decline or CTCAE toxicity, nearly half recovered by last follow-up. Bladder and rectum dose were significantly associated with patient- and physician-reported toxicity.

Abstract 3227 - Table 1

		Median EPIC Domain Score (Interquartile Range)
Time (mo)	N	UI	UO	BF	SF
Baseline	317	73 (53 – 98)	88 (75 – 95)	97 (91 – 100)	25 (13 – 54)
2	275	73 (52 – 100)	85 (75 – 95)	94 (84 – 97)	17 (5 – 39)
6	265	73 (52 – 94)	90 (80 – 95)	94 (91 – 100)	17 (8 – 53)
12	231	71 (52 – 92)	90 (80 – 95)	94 (88 – 97)	17 (8 – 54)
18	204	73 (52 – 94)	90 (75 – 95)	94 (88 – 100)	21 (8 – 51)
24	145	67 (49 – 94)	90 (80 – 95)	97 (91 – 100)	17 (8 – 40)
36	181	73 (48 – 92)	90 (80 – 95)	97 (91 – 100)	25 (13 – 57)
48	170	73 (52 – 94)	90 (80 – 100)	95 (88 – 100)	17 (13 – 45)
60	133	67 (46 – 92)	90 (80 – 98)	94 (88 – 100)	17 (12 – 42)