Radiation therapy might hurt men by inadvertently damaging their rectum. Men considering radiation therapy would be wise to ask their radiation oncologist about SpaceOar, a hydrogel product. SpaceOAR stands for Spacing Organs at Risk. Think of SpaceOar as a rectal spacer.  Hydrogel is a water-like substance that’s injected between the rectum and prostate in order to reduce the radiation dose to the rectum. Published studies have investigated it’s use with various kinds of radiation- IMRT, 3D-CRT, SBRT, protons, low dose rate brachytherapy, high dose rate brachytherapy, salvage radiation after primary prostatectomy, and salvage brachytherapy after primary radiation.  Those studies say hydrogel is usually safe and adds about 12mm of space between the rectum and prostate. 

Very few men will feel the hydrogel – it is fully absorbed by your body within a year and then pissed out.

SpaceOar may have a very useful role in men with bowel inflammation, a history of rectal issues (hemorrhoids, for example), or anatomic abnormalities.  SpaceOar may not be useful for men with late stage or advanced prostate cancer where the risk of rectal toxicity is trumped by the life extending potential of hitting the outside of the rectum with radiation.   For more information, please feel encouraged to read through  https://www.spaceoar.com/