Erectile Dysfunction and Absorbed Dose to Penile Base Structures in a Randomized Trial Comparing...

Area of Science:

• Radiation Oncology
• Urology
• Medical Physics

Background:

• Prostate cancer radiation therapy (RT) can cause erectile dysfunction (ED).
• Understanding dose-response relationships to penile structures is crucial for minimizing ED.
• Ultrahypofractionated (UHF) and conventionally fractionated (CF) RT have different dose distributions.

Purpose of the Study:

• To investigate the association between radiation dose to penile base structures and ED in prostate cancer patients.
• To compare ED rates and dose-response relationships between UHF-RT and CF-RT.

Main Methods:

• Dose-response study of 673 patients from the HYPO-RT-PC trial comparing CF and UHF RT.
• Retrospective delineation of penile bulb (PB) and crus on CT scans.
• Analysis of dose-volume parameters and patient age as predictors of severe ED (EDs) using regression models.

Main Results:

• No significant difference in EDs rates between CF and UHF groups (27% in both).
• Age was the strongest predictor for EDs.
• Penile bulb dose, specifically D2% (near maximum dose), emerged as a significant predictor in multivariable analyses.

Conclusions:

• ED rates were similar between CF and UHF RT for prostate cancer.
• Patient age and PB radiation dose are key predictors of ED, with younger patients being more susceptible.
• Proposed dose objectives for PB: D2% <50 Gy3 and Dmean <20 Gy3 to minimize ED risk.