Prostatic tissue testosterone and dihydrotestosterone in African-American and white men.

Objectives: To compare tissue androgen levels in the prostate gland of African-American and white men, looking for a possible explanation of the increased incidence of cancer in the former.

Methods: The subjects were 25 African-American and 36 white men, undergoing prostate biopsy consecutively, in whom cancer was absent. Biopsy cores (18 gauge) from the peripheral zone were homogenized, subjected to ether extraction, and separation by chromatography. Tissue testosterone and dihydrotestosterone (DHT) levels were determined by radioimmunoassay.

Results: The groups were matched for mean age (67.6 +/- 9.6 years), prostate volume (37.9 +/- 21.0 cm3), body mass index (28.2 +/- 4.2 kg/m2), and serum prostate-specific antigen (2.8 to 3.4 ng/mL) and testosterone (330 +/- 114 ng/dL) levels (P = NS for all measures). No significant difference in tissue testosterone (median 0.8 ng/g) or DHT (median 4.6 ng/g) was found between groups (P = NS). Furthermore, the tissue DHT/testosterone ratio (approximately 5) was not significantly different between the two groups (P = NS).

Conclusions: Prostatic tissue levels of testosterone and DHT were similar in African-American and white men; thus, the present data do not support a hypothesis of increased androgenic activity in African-American men. Because the ratio of DHT/testosterone in prostatic tissue was similar in the two groups, the possibility of increased 5-alpha-reductase activity in African-American men did not seem likely. Using needle biopsy specimens, both absolute values and the ratio of the androgens in prostatic tissue were similar to those found in previous studies using surgically excised glands. Thus, quick-frozen biopsy cores appear to be a valuable tissue source for evaluating the androgen status within the prostate.