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Location: Marriott Marquis
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PQA 06 - PQA 06 Biology and Patient Reported Outcomes/QoL/Survivorship Poster Q&A

2815 - Urinary Quality of Life in Patients Treated with Prostate SBRT with Intra-Prostatic Boost

Monday, September 30, 2024
5:00 PM – 6:00 PM ET
Location: Hall C

Screen: 9

M. Hurwitz, N. Bhargava, L. Bennett, J. A. Aronovitz, D. R. Schmidt, I. D. Kaplan, and N. Aghdam; Department of Radiation Oncology, Beth Israel Deaconess Medical Center, Boston, MA

Purpose/Objective(s): SBRT is a standard of care treatment for localized prostate cancer. Dose escalation improves outcomes for prostate cancer and concomitant intraprostatic boost (IPB) may offer an acceptable approach for dose escalation while maintaining tolerable dose to organs at risk. In this series, we report changes in IPSS score over a 12-month period following SBRT with IPB in patients treated in at a single academic institution with routine collection of pre- and post-treatment IPSS surveys. Materials/

Methods: Eighty-one patients treated from October 2018 to March 2022 received robotic stereotactic body radiotherapy with fiducial tracking and completed IPSS questionnaires. IPSS scores were evaluated for patients at three time points: pre-treatment, post-treatment, defined as 3 months after SBRT completion, and at follow-up, defined as within 12 months after SBRT completion. Patients who experienced minimally important difference (MID) in their post-treatment IPSS score comprised cohort A and those who did not comprised cohort B. Critical urethral and bladder doses were retrospectively extracted from the treatment planning software. Using a programming environment, two sided, two-sample t-tests were performed to compare dosimetric parameters between the two cohorts.
Results: Of the 81 total patients, 47 experienced MID. For cohort A, IPSS score medians and ranges were 8 (0-29), 6 (1-19), and 6.5 (0-31) for pre-treatment, post-treatment, and at 12-month follow-up, respectively. For cohort B, the medians and ranges were 5 (0-21), 12 (5-28), and 8.5 (1-32), respectively. A summary of median dosimetric parameters for each cohort is shown in the accompanying table. Max dose to (D0.03cc) to bladder was the only statistically different dosimetric parameter between the cohorts.

Conclusion: IPB is well tolerated with minimal change in urinary quality of life metrics as measured by IPSS. Max dose to the bladder remains the only significant difference in patients who experienced MID in their quality of life. Abstract 2815 – Table 1
A B p-value
D0.03cc Urethra 44.3 Gy 43.6 Gy 0.54
D0.3cc Urethra 43.1 Gy 39.8 Gy 0.71
V4000cGy Urethra 1.0cc 0.99cc 0.96
D0.03cc Bladder 42.2 Gy 40.4 Gy 0.002
D5cc Bladder 34.8 Gy 34.1 Gy 0.14
D10cc Bladder 30.8 Gy 30.2 Gy 0.41
V3700cGy Bladder 2.7cc 2.3cc 0.09