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Estradiol aromatization mediates testosterone effects on prostate
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Aromatization to estradiol mediates the tropic effects of testosterone on the prostate, according to study findings published in The Journal of Clinical Endocrinology & Metabolism.
No detrimental effects to the prostate were found with administration of aromatase inhibitors for 12 months in older men, researchers wrote.
Shehzad Basaria, MD, associate professor at Harvard Medical School, and colleagues evaluated 31 men aged at least 65 years with total testosterone less than 350 ng/dL to determine the effects of testosterone and estradiol on prostate volume. Participants were randomly assigned to 5 g transdermal testosterone gel (n = 11), 1 mg oral aromatase inhibitor (n = 11) or placebo (n = 9) daily for 12 months.
From baseline, total testosterone levels significantly increased into the target range (500-1,000 ng/dL) in both treatment groups. No change was found in serum testosterone level at 12 months in the placebo group; an increase from baseline was observed in both treatment groups. The testosterone group had increased serum total estradiol from baseline while the aromatase inhibitor group experienced a decrease.
Compared with baseline, prostate volume significantly increased at 12 months in the testosterone gel group (P = .03) but did not change significantly in the other two groups.
At 6 months, serum prostate-specific antigen levels increased in the testosterone gel group (P = .02) and the aromatase inhibitor group (P = .0006) compared with baseline; these levels decreased and remained slightly above baseline levels at 12 months.
“This proof-of-concept study demonstrated that the tropic effects of testosterone on the prostate are mediated via its aromatization to estradiol. ... As the use of [aromatase inhibitors] might impact bone mass negatively, the safety parameters of such a trial should include evaluation of bone mineral density and assessment of fracture risk,” the researchers wrote. “Without ensuring safety of the male skeleton, the clinical use of [aromatase inhibitors] cannot be advocated even in the absence of any harm to the prostate.” – by Amber Cox
Disclosure: Basaria reports receiving research grants from AbbVie and consulting fees from Eli Lilly and Takeda. No other researchers report relevant financial disclosures.
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