Here is a copy of an article from Medscape:

No Link Between Androgen Levels and Risk for Prostate Cancer


Zosia Chustecka

January 29, 2008 — Blood levels of androgens and other sex hormones
do not appear to be related to the risk for prostate cancer. The
finding comes from a huge pooled analysis of data from 18 studies,
published online January 29 in the Journal of the National Cancer
Institute. It "confirms the lack of evidence to support an androgen–
prostate cancer hypothesis," according to an accompanying editorial.
A link between elevated androgen levels and an increase in the risk
for prostate cancer has been widely hypothesized, despite little
supportive epidemiologic evidence, comment Paul Godley, MD, PhD, and
colleagues from the University of North Carolina, Chapel Hill, in an
accompanying editorial. Androgens play a key role in the development
of the prostate, and androgen suppression in advanced cancer can lead
to a dramatic regression of the disease, they point out. Hence, there
has been an "intense and sustained interest in confirming an androgen-
driven hypothesis," they add.
The new analysis provides no evidence of such a link, however. An
international collaboration of researchers, headed by Andrew Roddam,
DPhil, from the University of Oxford, United Kingdom, took another
look at the original data collected in the 18 studies, consisting of
3886 men with prostate cancer and 6438 controls. Each of the studies
had looked at the relation between androgens and the risk for
prostate cancer, but the results were inconclusive; some suggested a
positive association, but many of the studies had limited power, the
researchers comment. In the new analysis, all of the data from these
previous studies were pooled together. The team looked at blood
samples taken before the men developed prostate cancer and analyzed
serum concentrations of testosterone, free testosterone,
dihydrotestosterone, dehydroepiandrosterone sulfate, androstenedione,
androstanediol glucuronide, estradiol, and calculated free estradiol.
They found no significant relation between the serum levels of any of
these hormones and the risk of developing prostate cancer.
This is an "impressive pooled analysis" that enhances "our
understanding of prostate cancer epidemiology," the editorialists
comment. It also offers a new opportunity, because it now "obliges
the scientific community to move past a seductive, clinically
relevant, and biologically plausible hypothesis and get on with the
difficult task of exploring, analyzing, and characterizing modifiable
risk factors for prostate cancer."
However, the question of where to go from here will take some serious
discussion and debate, Dr. Godley commented to Medscape
Oncology. "I'm pretty sure that there is not an obvious answer to
what are the most likely causes of prostate cancer," he said.
The finding also raises questions about the use of finasteride for
the prevention of prostate cancer. This drug, a 5-alpha reductase
inhibitor, blocks the conversion of testosterone into the more potent
dihydrotestosterone. In the Prostate Cancer Prevention Trial,
previously reported by Medscape Oncology, finasteride reduced the
occurrence of prostate cancer by approximately 25% during a 7-year
period, although the risk for high-grade tumors was higher in the
treated group than in the untreated group. These results offer
a "tantalizing possibility for effective prostate cancer
chemoprevention," add the editorialists, but the hypothesis that
provided the theoretical foundation for this trial has now
been "convincingly debunked" by the latest finding.
However, this finding will probably not affect the use of finasteride
for prostate cancer prevention, even though it undermines part of the
rationale for its use, Dr. Godley commented to Medscape
Oncology. "I'm not sure that finasteride is being used much for that
purpose anyway." In addition, the theory is a little different in
each of these 2 trials, he pointed out. The current study set out to
investigate whether high androgen levels increase the risk for
prostate cancer, and showed that they do not, whereas the finasteride
trial set out to determine whether lowering androgen levels reduces
the risk for prostate cancer, and showed that it did.