Men using female oestrogen hormone replacement
therapy (HRT) patches as treatment for advanced prostate cancer suffer fewer
side-effects such as osteoporosis than with current treatments.
The male sex hormone, testosterone, causes the growth of the prostate
gland and other sex organs in men. Even as men pass through the age of
puberty, testosterone continues to contribute to the growth of the organ.
Testosterone will fuel the growth of any prostatic cell: the chemical cannot
discriminate between the receptors of healthy tissue and cancerous tissue.
Prostate cancer hormone therapy removes the chemical (testosterone) that
“feeds” cells and can stop or slow the growth and spread of prostate tumors.
Owing to cardiovascular and thromboembolic toxicities, oral estrogens
were abandoned as treatments for prostate carcinoma; however, it is now
recognized much of this toxicity can be avoided by parenteral (intramuscular
or transdermal) estrogen administration. Ockrim and coauthors highlight the
cost and protective andropause advantages of estrogen therapy, advocating a
re-evaluation of this promising, but forgotten therapy. Nature Clinical
Practice Oncology (2006) 3, 552-563doi:10.1038/ncponc0602
11 November 2006 | Accepted 14 June 2006
Estrogen is the female sex hormone and cannot feed the prostatic tissue,
but the hypothalamus will mistake estrogen for testosterone and stop GnRH
production. This halts testosterone production and a drop in testosterone
levels ensues. In most therapies which halt testosterone, a major side
effect is osteoporosis or bone loss. Osteoporosis is a debilitating
condition where bone-producing cells (osteoblasts) fail to keep up with
bone-removing cells (osteoclasts). These normally function together in
equilibrium, maintaining the skeleton in optimum condition. Approximately
10% of bone mass is removed and replaced each year, but current prostate
cancer treatments using LHRH agonists (Lupron & Zoladex) tamper with this
equilibrium, leading to bone weakening and susceptibility to fracture.
Estrogens have historically been used in the treatment of prostate
cancer. For many years, a synthetic estrogen, diethylstilbestrol or DES, has
been a mainstay in therapeutic regimens, primarily directed against
late-stage disease. While DES-based therapy does cause regression of many
prostate cancers, this treatment protocol often causes many untoward
effects, including those on the cardiovascular system. New evidence shows
that estrogen delivered via skin patches is effective as DES without many of
the side effects.
For the first time, a team led by Mr Paul Abel and Professor El-Nasir
Lalani, consultants at Hammersmith Hospitals NHS Trust and Imperial College
London, has shown that estrogen patches prevent bone loss. In the Journal of
Urology* they report that estrogen skin patches can increase bone density in
patients with advanced cancer. The team found using these patches, commonly
used to relieve menopausal symptoms in women, increased bone density by an
average of more than 3% after a year on the 20 men treated. This in addition
to the fact that t
"The considerable promise of parenteral oestrogen in advanced prostate
cancer has already been reported by our team, but the additional benefit of
preventing bone loss is extremely exciting news," comments Mr Abel.
"Osteoporosis was once seen as a women’s disease, but has become an
increasingly important consideration in prostate cancer as patients survive
with the disease for longer periods of time."
The study followed 20 men with late stage prostate cancer who were given
oestrogen hormone replacement therapy skin patches. After an initial
pre-treatment measurement of bone mineral density in the spine and femur
using X-ray (DXA scanning) techniques, the patients returned after six
months and a year for check-ups.
