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No link between short-term testosterone use and prostate cancer, study says

May 22, 2006

Los Angeles, Calif. - Testosterone therapy does not cause adverse effects on the prostate in older men with hypogonadism, commonly known as low testosterone or low T, according to a clinical trial presented today at a national urology meeting in Atlanta. The study, which focused on direct measurement of testosterone in prostate tissues, carries important implications for the millions of men with low testosterone, who may benefit from testosterone replacement therapy. Results from the study were presented in two abstracts at the American Urological Association annual meeting.

"We found no evidence that testosterone replacement therapy negatively affects the prostate or its tissues in hypogonadal men following six months of treatment," said Dr. Leonard Marks, co-investigator, Clinical Associate Professor in the Department of Surgery/Urology at the UCLA School of Medicine and founding medical director of Urological Sciences Research Foundation (USRF). "Patients should be comforted by these results, but large-scale, long-term trials are still needed."

Testosterone is a hormone involved in regulating prostate growth, both benign and malignant. When testosterone is boosted, the effect on the prostate is a main concern in older men. However, this study showed that when serum testosterone levels are increased to the mid-normal level, the prostate effects are minimal, at 6-months.

In the randomized, placebo-controlled clinical trial, investigators examined the effects of testosterone (T) in 41 men, ages 50-75 years old with hypogonadism (ADAM score and morning T<300 ng/dL) for a 6-month period. Twenty-one men received testosterone intramuscular injections (150 mg every two weeks); 20 men received placebo. The study was powered to detect a 25% increase in dihydrotestosterone (DHT) in prostate tissue. The groups were comparable at baseline for age, serum T and DHT, Prostate-Specific Antigen (PSA), Prostate Volume (PV) and median prostate levels of T and DHT. Prostate biopsies were conducted at baseline and at 6-months.

No prostate tissue changes attributable to testosterone therapy were found in this trial. Despite marked increases in serum testosterone levels, prostate levels of T and DHT (the hormone that stimulates prostate gland growth) did not change from baseline at 6-months. PSA, PV, tissue biomarkers and indices for atrophy and inflammation also were unchanged after 6-months of treatment. Furthermore, gene expression was not altered, cell proliferation was not accelerated, and histologic cancers were not increased. The study also showed testosterone therapy created positive effects in bones and muscles.

"The prostate appears to be buffered against rather wide fluctuations in serum testosterone levels," said Dr. Marks. "Still, all hypogonadal men considering testosterone therapy, especially older men, must be monitored closely by their physicians prior to and throughout treatment."

Urological Sciences Research Foundation