SAN DIEGO—Testosterone treatment is not associated with an increased likelihood of being diagnosed with prostate cancer (PCa), and it may lower the risk aggressive PCa, according to the findings of separate studies presented at the American Urological Association 2016 annual meeting.

In a study of 147,593 US veterans with low total testosterone, Thomas J. Walsh, MD, of the University of Washington in Seattle, and colleagues found that PCa incidence was per 1,000 person-years was 2.27 among men who ever received testosterone treatment and 2.60 in those who never received treatment. In adjusted analyses, ever-treatment with testosterone was not associated with increased the overall PCa risk and risk of aggressive PCa compared with no testosterone treatment.

Of the entire cohort, 56,833 men (40%) received testosterone therapy. Of these, 40% received intramuscular testosterone only, 38% received topical testosterone only, and 22% received both types of preparations. The median follow-up for all men was 3.0 years, 3.2 years for men testosterone treated men and 2.8 years for untreated men. A total of 1,439 PCa cases were diagnosed (1%). Of these, 313 were aggressive.

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The finding of no association between testosterone therapy and PCa risk held regardless of testosterone formulation and lifetime cumulative dose.

“Among veterans with low testosterone levels, compared to no treatment, testosterone treatment was not associated with increased risk of subsequent prostate cancer diagnosis, any prostate cancer or high grade,” Dr. Walsh said at a press conference.

In another study, Ahmad Haider, MD, a urologist in private practice in Bremerhaven, Germany, and colleagues found that long-term treatment with testosterone was associated with a lower incidence of PCa and less aggressive PCa among those diagnosed with the malignancy. The study included 656 hypogonadal men. Of these, 360 received testosterone treatment and 296 opted against treatment and served as controls.

PCa was diagnosed in 7 men (1.9%) in the testosterone group and 12 (4.1%) of the control group. The PCa incidence per 10,000 patient-years was 30.0 in the testosterone group versus 63.5 among controls.

All PCa patients underwent radical prostatectomy. Among those treated with testosterone, the predominant Gleason score was 3 and the tumor grade was 2 in all patients. All had negative lymph nodes and surgical margins. In the control arm, the predominant Gleason score was 3 in 3 patients, 8 in 4, and 5 in 1. The tumor grade was 2 in 5 men and 3 in 7 men. In addition, 7 men had positive lymph nodes and 7 had positive surgical margins.

“Long-term treatment with testosterone in hypogonadal men may reduce the incidence of prostate cancer and protect against high-grade prostate cancer,” Dr. Haider concluded.