Effects of Transdermal Testosterone Gel or an Aromatase Inhibitor on Prostate Volume in Older Men.

CONTEXT

T replacement is being increasingly offered to older men with age-related low T; hence, monitoring prostate health is important during T therapy. Data suggest that estrogens have an independent effect on the prostate and some effects of T on the prostate might be mediated via its aromatization to estradiol. Although some studies have assessed the effects of T replacement on prostate volume, the differential effects of T and estradiol have not been delineated.

OBJECTIVE

The objective of the study was to investigate the relative effects of T and estradiol on prostate volume in older men with low T.

PARTICIPANTS

Thirty-one men, 65 years old or older with total T less than 350 ng/dL (measured by mass spectrometry) participated in the study.

INTERVENTION

The intervention included randomization to 5 g transdermal T gel (TT), 1 mg oral aromatase inhibitor (AI), or placebo daily for 12 months.

MAIN OUTCOME MEASURES

The primary outcome was prostate volume measured by transrectal ultrasound at baseline and 12 months. Secondary outcomes included prostate-specific antigen levels and lower urinary tract symptoms score.

RESULTS

Serum T levels increased in both intervention groups; estradiol levels increased in the TT group, whereas it decreased in the AI group. At 12 months, prostate volume significantly increased (4.5 ± 1.76 cc, P < .05) only in the TT group. Increase in prostate-specific antigen levels were seen in both intervention groups at 6 months (P < .01 and P < .001). The lower urinary tract symptoms score increased only in the TT group (P < .05).

CONCLUSIONS

The tropic effects of T on the prostate are mediated via its aromatization to estradiol. Administration of AI for 12 months to older men was not detrimental to the prostate.