Could radiation for prostate cancer cause rectal bleeding?

Yes: One of the potential side effects for radiation therapy to treat prostate cancer is rectal bleeding. This can occur after brachytherapy or external beam therapy. This is called proctitis and is generally mild and self-limiting. It usually does not require any treatment other than conservative management such as maintaining soft bowel movements, hydration, and monitoring of blood work.

Yes: External radiation with latest method which is image guided has minimized the dose to the rectum but it is still possible and fairly common. Most cases resolve and easily managed but can be a recurring issue. I find rectal bleeding almost zero or less chance of happening in radiation with seeds or brachytherapy radiation methods.

Yes. But usually: Years after. Bleeding during radiotherapy is usually hemorrhoids. Proctitis occurs in 2-15% between 3 and 10 years with modern treatment, and mostly can be arrested by simple endoscopic procedure and a laser like treatment. Bladder and rectal problems are of low frequency now.