Soft constraints

January 05, 2023

Soft constraints.

Can prostate radiation be optimized to reduce post-treatment erectile dysfunction? In this single-center trial, 117 patients receiving conventionally fractionated radiation (74-80 Gy in 37-40 fractions) for low to intermediate risk prostate cancer were randomized to standard IMRT planning or erectile tissue sparing IMRT with the use of specific constraints for the penile bulb and corporal bodies. The corporal bodies are just lateral to the penile bulb on axial imaging. The penile bulb and corporal body constraints were D90 <15 Gy and <7 Gy, respectively. Nobody received ADT. Prior to enrollment, all patients were “potent” meaning they were able to achieve satisfactory erections >50% of the time. At 24 months after treatment of patients with complete follow up evaluation, there was no difference in the somewhat disappointing rate of preserved potency with erectile tissue sparing IMRT (48% v 46%). There was also no difference in the rate of PDE5 inhibitor use after RT (42% v 35%).