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

Abstract

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.

Trial registration: ClinicalTrials.gov NCT00104572.

Figures

Figure 1.

Change in gonadal steroids and gonadotropins after 12 months of intervention. Data are expressed as mean ± SEM. *, P < .05, **, P < .01, ***, P < .001 compared with placebo; ++, P < .01, +++, P < .001 compared with baseline values.

Figure 2.

Change in prostate volume after 12 months of intervention. Data are expressed as mean ± SEM. +, P < .05 compared with baseline values; *, P < .05 compared with placebo.

Figure 3.

Change in serum PSA levels after 12 months of intervention. Data are expressed as mean ± SEM. ++, P < .01, +++, P < .001 compared with baseline values.

Figure 4.

Change in IPSS after 12 months of intervention. Data are expressed as mean ± SEM. *, P < .05 compared with placebo.