Stiff constraints.

HYPO-RT-PC was the first reported randomized trials of ultra-hypofractionated radiation for prostate cancer, in which men were randomized to either 2 Gy x 39 = 78 Gy or 6.1 Gy x 7 = 42.7 Gy. This secondary analysis retrospectively looks at dosimetric associations with erectile dysfunction. It included only men with “potent” erections at enrollment (57% overall) in whom they went back to draw the penile bulb and crus. The big takeaway was that there was no difference in the rate of subsequent erectile dysfunction with respect to regimen. What was the biggest predictor? The completely non-modifiable age at time of treatment. But this was followed by the D2% of the penile bulb with a concluding recommendation for D2% < 50 Gy and mean dose < 20 Gy in EQD2 (alpha/beta 3). TBL: Limiting dose to the penile bulb can limit risk for radiation-induced erectile dysfunction, particularly at younger ages, and regardless of fractionation schema. | Rasmusson, Int J Radiat Oncol Biol Phys 2020