Prostate cancer treatment side effect no one talks about: shrinkage

When oncologists run through the list of possible side effects of surgery and other treatments for prostate cancer, rarely mentioned is one that leaves some men to regret their treatment choice: shrinkage.

Yet a significant percentage of men who undergo surgery to remove their prostate gland or hormone therapy combined with radiation report that they experience a decrease in their penis size after treatment, which can affect their relationships and quality of life, Dana-Farber Cancer Institute researchers found in a new study.

Radiation treatments alone did not lead to a reduction in penis size, according to the study published Wednesday in the journal Urology.


The researchers examined surveys from 948 men recently treated for prostate cancer and found that nearly 3 percent of patients complained of a reduced penis size following treatment. But study co-author Dr. Paul Nguyen, a radiation oncologist at Dana-Farber, called this a significant underestimate because men often feel uncomfortable discussing this side effect with their doctors — and doctors often don’t ask about it.

Men in the study who reported complaints about penis shrinkage were more than three times as likely to regret their treatment choice than those who had no complaints.

The surveys provided to oncologists who participated in the study included dozens of questions, including ones about sexual side effects such as impotence and ejaculation problems. “We’re not sure in what detail doctors asked patients about penis size,’’ said Nguyen.

In previous studies where researchers actually measured penis size after surgery, the average loss in size was about 1 centimeter. (That’s when not erect but stretched.) “About 70 percent of men had some reduction in length, but many didn’t notice it, especially if it was just a few millimeters,’’ Nguyen said.

Reasons for why surgery and a combination of hormone therapy with radiation may lead to a reduction in penis size remain unknown but could be due to tissue loss that occurs after these treatments. And surgeons sometimes need to pull in certain nerves and blood vessels to reattach them after the prostate gland is removed, which could change the organ’s length.


A recent small study suggested that the condition might reverse after five years, but Nguyen said that needs to be confirmed by larger studies. In the meantime, patients considering surgery or a combination of hormone therapy and radiation should ask their doctor about this side effect if they’re concerned about it.

“It’s definitely something I talk to my patients about,’’ Nguyen said, “but the onus may be on patients to raise the issue if their doctor fails to bring it up.’’

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