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SU_23_2232 - A Prospective Cohort Study of Patient Reported Outcomes and Late Toxicity in Patients Receiving Post-Prostatectomy Intensity Modulated Radiation Therapy (IMRT)

Sunday, October 21
1:15 PM - 2:45 PM
Location: Innovation Hub, Exhibit Hall 3

A Prospective Cohort Study of Patient Reported Outcomes and Late Toxicity in Patients Receiving Post-Prostatectomy Intensity Modulated Radiation Therapy (IMRT)
A. S. Akthar1, C. Liao2, and S. Liauw1; 1The University of Chicago, Department of Radiation and Cellular Oncology, Chicago, IL, 2The University of Chicago, Department of Public Health Sciences, Chicago, IL

A Prospective Cohort Study of Patient Reported Outcomes and Late Toxicity after Post-Prostatectomy Intensity Modulated Radiation Therapy (IMRT)

Purpose/Objective(s): The primary goal of this study was to characterize patient reported quality of life (QOL) and late toxicity in patients receiving post-prostatectomy IMRT.

Materials/Methods: A consecutive cohort of 199 men (mean age of 63) with prostate cancer after radical prostatectomy received IMRT between 2007-2015 using predefined planning guidelines. Patients were prospectively evaluated using the Expanded Prostate Cancer Index Composite (EPIC-26) instrument and RTOG/CTC toxicity grades at baseline and follow up. Treatment was delivered to the prostate bed (median 68 Gy) +/- pelvic lymphatics (65%, median 50.4 Gy) with daily image guidance. 132 (66%) men received androgen deprivation therapy (ADT) for a median of 4 months. Patients were seen at 2 mo, then q6-12 mo up to 84 months. Wilcoxon signed-rank tests compared changes in QOL between baseline and each time point. Generalized estimating equation (GEE) models and Cox regression were used for multivariate analysis (MVA) to identify factors impacting each QOL domain and freedom from ≥ grade 2 (FFG2) gastrointestinal (GI) or genitourinary (GU) toxicity, respectively. Dosimetric data analyzed included the V70, 65, and 40 Gy for bladder and rectum and mean penile bulb dose.

Results: Median time from radical prostatectomy to RT was 19 mo.  The median V70/65/40 Gy to the bladder and rectum were 18/45/73% and 6/22/54%, respectively. Median follow-up was 33 months with 27% of patients providing 5-year outcomes. Overall urinary(U), bowel(B), sexual(S), and urinary irritation/obstruction (UI/UO) domains declined at 2 months. These domains and urinary continence (UC) also showed a decline at 18 mo (P<0.05) which was less than the minimally important difference. FFG2 GU and GI toxicity were 82% and 89%, respectively at 4 years.  Factors impacting QOL and toxicity on MVA are shown in table 1. Only BMI was significant on univariate analysis for GI toxicity. Table 1: Multivariate analysis
QOL Domain Covariates

Coefficient [95% CI]

P value

UC Baseline score Age Bladder V70 Gy .65 [.56,.74] -.37 [-.70,-.04] -.37 {-.58,-.17] <.001 .03 <.001
UI/UO Baseline score Age Bladder V70 Gy Never smoker .41 [.30,.53] -.23 [-.43,-.03] -.15 [-.27,-.03] 4.8 [.36,9.1] <.001 .02 .02 .03
U Baseline score Age BMI Bladder V70 Gy .64 [.54,.74] -.34 [-.56,-.12] -.30 [-.57,-.03] -.25 [-.39,-.11] <.001 .004 .03 <.001
B Baseline score .58 [.48,.68] <.001
S Baseline score Pelvic nodal RT .61 [.51,.70] -5.8 [-11.1,-.60] <.001 .01
Toxicity Covariates Hazard ratio [95% CI] P value
GI N/A N/A N/A
GU Age ADT Diabetes Baseline UI/UO QOL 1.06 [1.01,1.12] 2.55 [1.10,5.87] 2.45 [1.04,5.77] .98 [.97,.99] .02 .03 .04 <.001

Conclusion: Long term QOL and late toxicity are favorable following post prostatectomy IMRT. Certain clinical and dosimetric factors may help guide decision making in consideration of preserving QOL.

Author Disclosure: A.S. Akthar: None. C. Liao: None. S. Liauw: None.

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SU_23_2232 - A Prospective Cohort Study of Patient Reported Outcomes and Late Toxicity in Patients Receiving Post-Prostatectomy Intensity Modulated Radiation Therapy (IMRT)



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