Medical Research: What are the main findings of the study?
Dr. Bosland: The two main findings are :
(1) that long-term, low-dose testosterone treatment induces prostate cancer in rats (none occurred in control rats) and increases the number of rats with malignant tumors at any site in the body compared to control rats, and
(2) that in rats treated long-term with testosterone after a single prostate-targeted chemical carcinogen treatment a high incidence of prostate cancer is induced, even at a very low testosterone dose.
Medical Research: What was most surprising about the results?
Dr. Bosland: Most surprising was the high incidence of prostate cancer in rats that were treated long-term with a after a single prostate-targeted chemical carcinogen treatment; this very low dose of testosterone did not significantly raise blood levels of this hormone compared with control rats.
Medical Research: What should clinicians and patients take away from your report?
Dr. Bosland: These results suggest that testosterone may also increase the risk of prostate cancer in humans. However, there are not yet adequate epidemiology studies of men on testosterone therapy to determine whether this is the case. Therefore, it appears prudent to limit testosterone therapy to those men who suffer from symptomatic clinical hypogonadism, to consider the low testosterone blood levels that occur in aging men a normal phenomenon and not a disease that requires treatment, and to avoid testosterone use by men for nonmedical purposes.
Medical Research: What recommendations do you have for future research as a result of this study?
Dr. Bosland: Retrospective and prospective epidemiology studies of men on testosterone therapy are urgently needed, because the currently available studies are of too short a duration and include too few subjects.