Erections and pelvic radiation therapy

Prostate, bladder, and colon cancer are often treated with radiation to the pelvis. This can cause problems with erections. The higher the total dose of radiation and the wider the section of the pelvis treated, the greater the chance of an erection problem later.

One way that radiation affects erection is by damaging the arteries that carry blood to the penis. As the irradiated area heals, the blood vessels lose their ability to stretch due to scar tissue in and around the vessels. They can no longer expand enough to let blood speed in and create a firm erection. Radiation can also speed up hardening (arteriosclerosis), narrowing, or even blockage of the pelvic arteries. Radiation may also affect the nerves that control a man’s ability to have an erection.

A reasonable estimate is that one-quarter to one-third of the men who get radiation will notice that their erections change for the worse over the first year or so after treatment. This change most often develops slowly. Some men will still have full erections but lose them before reaching climax. Others no longer get firm erections at all.

In older studies, about 3 out of 4 men were impotent within 5 years of having external beam radiation therapy (though some of these men had erection problems before treatment). In men who had normal erections before treatment, about half had become impotent at 5 years. It’s not clear if these numbers will apply to newer methods that better limit radiation exposure to normal tissue.

As with surgery, the older you are, the more likely it is you will have problems with erections. And men with heart or blood vessel disease, diabetes, or who have been heavy smokers seem to be at greater risk for erection problems. This is because their arteries may already be damaged before treatment. Doctors are looking at whether early penile rehabilitation, discussed under “Early sexual rehabilitation after surgery” in the “Erections and pelvic surgery to treat cancer” section may be helpful after radiation therapy, too.

In a few men, testosterone production will slow after pelvic radiation. The testicles may be affected either by a mild dose of scattered radiation or by the general stress of cancer treatment. If a man notices erection problems or a loss of desire after cancer treatment, his first thought may be that he needs to have a blood test for testosterone. But testosterone levels usually get back to normal within 6 months after radiation therapy, so extra hormones may not be needed. And men with prostate cancer should not take testosterone, since it can speed up the growth of prostate cancer cells.