Another Reason Reconsider Radiation Treatment: Low Testosterone

Men with localized prostate cancer (PCa) are usually given three treatment choices: radical prostatectomy (RP), external beam radiation therapy (EBRT) or Active Surveillance (AS). Although patients are rarely told about minimal-to-noninvasive treatments that can be applied as focal therapy, it’s somewhat heartening that urologists and radiologists are increasingly supportive of AS for low-risk patients. This is good, because it avoids overtreating insignificant PCa and preserves urinary and sexual function until clinical factors would indicate a need for treatment.

These days, it seems like all PCa patients are aware of the possible side effects of RP and EBRT. The difference between those two modalities is a kind of “pay now or pay later” choice. RP (“pay now”) more frequently results in upfront post-treatment urinary incontinence and ED, with the hope that things will improve in a year or less. EBRT (“pay later”) has almost no upfront side effects other than fatigue and possibly some minor bowel irritation, but years down the line there could be urinary tract irritation, ED, and risk of secondary bladder or bowel cancers. However, a lot of patients are willing to have radiation or seed implants, because they don’t want the chance of surgical side effects. They prefer to take their chances further down the line.

A new international, multi-center journal article by Pompe et al. (2017)[i] reveals that EBRT has a sneaky side that has only rarely been studied: it leads to a drop in normal testosterone levels. Testosterone is measured by means of a blood test, so the results are usually referred to as serum testosterone levels. For this study, 248 patients who underwent EBRT from 2002 to 2014 had their pre-treatment (baseline) serum testosterone levels recorded, then they were reassessed after treatment according to each center’s protocol. The average follow-up was 72 months (6 years).

Here are the findings:

  • 186 patients (75%) showed a drop in testosterone after radiation.
  • Average time to the first measured drop was 6.4 months.
  • 112 (45.2%) developed insufficient testosterone, a condition called hypogonadism.
  • Of all who had a drop in testosterone, 117 (62.9%) recovered “to at last 90% of baseline levels”.

Thus, while most patients whose testosterone is affected will eventually recover, the article’s summary is somewhat shocking: “Our findings indicate that up to 75% of patients treated with EBRT monotherapy [meaning radiation alone, no hormones or other additional treatment] will have a profound testosterone decrease, with up to a 40% increase in rates of biochemical hypogonadism [insufficient serum testosterone]…” Perhaps what’s most sobering is the realization that since the testes produce testosterone, the scatter effect of radiation affects how well the testes are able to function until they recover from radiation exposure.

The Canadian Cancer Society notes: “The testicles are very sensitive to the effects of radiation. Radiation can reduce the number of sperm produced or damage sperm and affect their ability to function. Temporary or permanent infertility (inability to father a child) can occur because of radiation to the testicles.”[ii] Even though EBRT for prostate cancer is not directly aimed at the testicles, the Pompe study demonstrates that not just sperm production can be affected by radiation, but the very hormone that defines masculinity has a high risk of a steep decrease.

Patients who have EBRT should be made aware of the risks they face, including late onset urinary, sexual or bowel complications in addition to effects on sperm production. Yet those who choose AS take a different kind of chance, since they are hoping to hold off on treatment as long as possible but not to the point where they miss a treatment window.

It’s no wonder that more PCa patients are turning to focal treatments that will control their disease but avoid diminishing their manhood and lifestyle.


[i] Pompe RS, Karakiewicz PI, Zaffuto E, Smith A et al. External beam radiotherapy affects serum testosterone in patients with localized prostate cancer. J Sex Med. 2017 May 22. pii: S1743-6095(17)31140-2. doi: 10.1016/j.jsxm.2017.04.675. [Epub ahead of print]

[ii] http://www.cancer.ca/en/cancer-information/diagnosis-and-treatment/radiation-therapy/side-effects-of-radiation-therapy/radiation-to-the-pelvis/radiation-effects-on-men/?region=sk#ixzz4ihCbWKDL