Do some prostate cancer treatments affect penis size? Absolutely, say a research team headed by physicians at Dana-Farber/Brigham and Women’s Cancer Center in Boston, Massachusetts.1 Some treatments for prostate cancer do seem to result in a smaller penis, leading the patient to regret the type of treatment he chose to have.1


For their study, investigators researched the penis size of 948 men treated for prostate cancer by having their physicians complete a survey on each patient. The men were enrolled in the Comprehensive Observational Multicenter Prostate Adenocarcinoma (COMPARE) registry. The study results were published in Oncology.

Of the 948 men in the study, 22% were younger than 60 years.1 The majority of the participants were in their 60s, 70s, and 80s. Fifty-four percent of the men had undergone prostatectomy, 24% received radiotherapy combined with hormone-blocking treatment, and 22% of the men received radiotherapy alone.1

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The assessment for this study took place an average of 5.5 years after the participants were treated. The participants’ prostate cancer was treated with radical prostatectomy, radiotherapy (external beam radiation therapy or brachytherapy [implantation of radioactive seeds into the prostate]) with androgen deprivation therapy (ADT), and radiotherapy without ADT. A small percentage of the study participants (2.63%) complained of having a smaller penis after undergoing treatment. The study results correlated with the different treatment modalities.


Most of the participants who complained that their penises were shorter after treatment had undergone radical prostatectomy or RT combined with ADT, according to the researchers, whereas none of the men who underwent radiation therapy alone had complained. Some of the men who perceived that their penises were shorter also said the reduced size interfered with their intimate relationships and they regretted choosing the type of treatment they did.

Paul Nguyen, MD, a radiation oncologist at Dana-Farber, and Harvard medical student Arti Parekh led the research team.1 The researchers said that theirs is the first study connecting perception of a reduction in patients’ penis size to problems in their emotional relationships, lowered life satisfaction, and to regrets about the specific type of treatment the patient chose for his prostate cancer.1


According to the researchers, physicians are aware that a reduction in penis size can be a side effect of some prostate cancer treatment modalities; however, this is rarely explained to the patient. The researchers suggest that this is wrong; the patient should be prepared for any side effect in order to make more informed choices about which treatment he would want.

The shortened penis length is most often a result of non-nerve sparing surgery, which can cause fibrosis and atrophy of erectile tissue due to nerve and vascular damage, the study authors explained. Prior studies have confirmed this. But again, it is not usually discussed with the patient before surgery. The men’s physicians did not directly measure the penis before or after surgery. Nor did they bring up the subject in conversations with their patients. The only time a discussion about penis size came about was when the patient himself brought up the subject. Since it is just not a common topic of conversation, the study authors theorize that the problem may be more prevalent than reported in this study.


“Prostate cancer is one of the few cancers where patients have a choice of therapies, and because of the range of possible side effects, it can be a tough choice,” said Nguyen. “This study says that when penile shortening does occur, it really does affect patients and their quality of life. It’s something we should be discussing up front so that it will help reduce treatment regrets.”1 ONA

Bette Weinstein Kaplan is a medical writer based in Tenafly, New Jersey.


1. Parekh A, Chen MH, Hoffman KE, et al. Reduced penile size and treatment regret in men with recurrent prostate cancer after surgery, radiotherapy plus androgen deprivation, or radiotherapy alone. Urology. 2013;81(1):130-135.