POSTED: September 27, 2018

Erectile Dysfunction After Radiation

Dr. Irving Kaplan is a radiation oncologist at Beth Israel Deaconess Medical Center and an Assistant Professor at Harvard Medical School.

Prostatepedia spoke with him about erectile dysfunction after stereotactic body radiotherapy (SBRT).

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Why did you become a doctor?

Dr. Irving Kaplan: I started out as a basic researcher. But when I was in medical school, I realized I’d much rather deal with people than petri dishes. I decided to do clinical medicine.

Have you had any particular patients who’ve changed how you see your own role as a doctor?

Dr. Kaplan: Every patient brings something different. In your training as a radiation oncologist, you see patients all throughout the course of treatment, sometimes even in a palliative setting. You learn a lot from patients.

How common is erectile dysfunction (ED) after SBRT?

Dr. Kaplan: Evaluating erectile function after radiation has always been a difficult issue. We have to rely on patient questionnaires. If we relied on what the doctors recorded in their notes, it wouldn’t be valid because doctors overestimate how good their patients’ erections are posttreatment. We have to rely on patient-reported outcomes. And that’s very complex.

There are many factors that determine if a person will develop ED after treatment. Radiation doesn’t cut the nerves, but it does age them. If there’s a natural decline in a man’s function over time, radiation pushes them down along that curve by four to five years.

A young patient, meaning under 65 or so, who has good erections before treatment, has a 75 to 80 percent chance of having no change in his erections for two or three years. Further down the line, he can start to have problems, but it’s really no worse than with any other form of radiation. There are no direct comparative studies, though, in which half the patients got one form of radiation and the other half got another.

We do have models that people have created, though, in which you plug in a patient’s age, current function, whether or not he has diabetes, his body mass index, etc.—all things that impact erections —to predict his chances of having ED after external beam or brachytherapy.

Patients receiving radiosurgery are not statistically better or worse than those getting other forms of treatment.

What kinds of ED treatments are effective after SBRT?

Dr. Kaplan: There is a big difference in ED treatment after surgery versus ED treatment after radiation. After radiation, we use medicines called PDE5 inhibitors—Viagra (sildenafil), Cialis (tadalafil), and Levitra (vardenafil). If taken appropriately, these tend to work 80 to 85% of the time. We use these medicines in patients who have good erections and then start to develop some mild ED.

If someone already needs Viagra (sildenafil) or other medications before radiation, they often need a bump up in their dose after radiation but are also more likely to have longer-term issues.

In addition to medications, there are injections, vacuum devices, and penile prostheses.

Is there anything a man can do before SBRT to reduce his risk of ED after treatment?

Dr. Kaplan: I don’t think that has really been tried very much. With regular radiation, they did try using low-dose Cialis (tadalafil) during treatment. That study really didn’t show much of a benefit. The idea was that if you keep the blood flowing the way it normally should during radiation, that blood flow should be better after radiation.

It was a good idea, but it didn’t pan out.

Again, I’m not differentiating between radiosurgery and regular external beam or brachytherapy.

What advice would you give to patients about to undergo treatment?

Dr. Kaplan: Before I see a patient, I get a baseline in terms of their bowel, bladder, and sexual functioning through some standard questionnaires. This helps guide the discussion. Especially in younger patients who do have pretty good function, sexual function is always part of the discussion.

Again, there is no standard patient. Some patients can have very good erections, but they have decreased volume of ejaculate after radiation. You get that with surgery as well. For some men, that is a big deal.

We discuss all aspects of sexual functioning, not just erections.

A lot of men are nervous about taking drugs like Viagra (sildenafil) because they see the advertisements. One side effect listed in commercials on American TV is the possibility of prolonged erections of more than four hours. One patient who was in advertising thought that was a great advertising ploy.

Too many men, I think, who really want to have good erections are turned off by the medications but there usually aren’t any contraindications. They’re very widely prescribed. Patients should not be so scared about taking them. I have a lot of patients who complain bitterly. I give them a prescription, but the next time I see them, they haven’t filled the prescription because they’re scared, or their wife tells them not to do it.

There can be a lot of reluctance, but in my clinical practice, they are extremely well tolerated and can work.

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