New York—Long-term use of testosterone replacement therapy (TRT) does not appear to increase the risk of prostate cancer in men with low levels of the male sex hormone, according to a large review.

The analysis of more than a quarter-million medical records of mostly white men in Sweden was presented recently at the annual meeting of the American Urological Association in San Diego.

An international study team led by NYU Langone Medical Center researchers reported that men prescribed testosterone for longer than a year appeared to have no overall increase in risk of prostate cancer. In fact, study authors note, results suggest the risk of aggressive disease declined by 50%.

After adjusting for previous biopsies as an indicator of diagnostic activity, researchers found that TRT remained significantly associated with higher risk of favorable-risk prostate cancer and lower risk of aggressive prostate cancer.

“Based on our findings, physicians should still be watching for prostate cancer risk factors—such as being over the age of 40, having African-American ancestry, or having a family history of the disease—in men taking testosterone therapy, but should not hesitate to prescribe it to appropriate patients for fear of increasing prostate cancer risk,” explained lead study investigator Stacy Loeb, MD, MSc.

Androgen-deprivation therapy often is used as therapy for advanced prostate cancer to help decrease tumor growth by reducing male hormones, but Loeb points out that doesn’t mean that replacing the hormone promotes cancer, adding, “when used appropriately by men with age-related low testosterone who are otherwise healthy, testosterone replacement has been shown to improve sexual function and mood.”

Researchers reviewed the National Prostate Cancer Register (NPCR) and the Prescribed Drug Register in Sweden, focusing on 38,570 prostate cancer cases diagnosed from 2009 to 2012 and 192,838 age-matched controls. Results indicate that prostate cancer was diagnosed between 2009 and 2012 in 38,570 of the men whose records were examined.

Of those, 284 had prescriptions for testosterone-replacement therapy before they were diagnosed, compared to 1,378 of those in the group that didn’t develop prostate cancer.

TRT users had a higher risk of favorable-risk prostate cancer, odds ratio 1.35, and a lower risk of aggressive disease, OR 0.50. When stratifying by duration of TRT, the increased risk of favorable prostate cancer was observed already within the first year of TRT use, but the lower risk of aggressive disease was observed only after more than a year of TRT use.

Initial analysis showed a 35% increase in prostate cancer in men shortly after starting therapy, but study authors determined that the cancers were at low risk of spreading and that the diagnoses probably resulted from more doctor
visits as treatment was initiated.

Long-term reduction in aggressive disease was observed only after more than a year of testosterone use, with the risk of prostate cancer no different among gels or other types of preparations.

“TRT use was associated with an early increase in favorable-risk prostate cancer, suggesting a possible detection bias,” study authors conclude. “However, the finding of a lower risk of aggressive prostate cancer in the long-term among TRT users is a novel finding that warrants further investigation.”

“Overall, our study suggests that what is best for men's health is to keep testosterone levels balanced and within a normal range,” Loeb added in a New York University School of Medicine press release.

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