Hormone replacement therapy patches have considerable potential as prostate cancer therapy

Men using the female estrogen hormone replacement therapy (HRT) patches as treatment for advanced prostate cancer suffer fewer side effects than with other treatments, according to a new study reported in the latest issue of the Journal of Urology.

Scientists at Hammersmith Hospitals NHS Trust and Imperial College London have already shown that HRT patches have considerable potential as prostate cancer therapy. For the first time they have additionally shown that this therapy, unlike other current treatments, prevents bone loss (osteoporosis) and instead causes an increase in bone density. These early studies confirm the considerable promise of estrogen hormone patches in advanced prostate cancer.

Prostate cancer is the most common male cancer in the UK, with about 20,000 cases diagnosed every year. Affecting men generally over the age of 45, prostate cancer grows slowly and may go undetected for many years. In some cases, the cancer can spread to bones and other organs of the body. The causes of prostate cancer are mainly unknown, but it requires the male hormone testosterone, produced in the testicles, to develop and grow. Treatment of advanced disease has resulted in therapies that reduce or remove testosterone from the body, via surgical or medical ‘castration.’

“Depriving the cancer of testosterone is the well accepted method of slowing down the progression of advanced prostate cancer,” comments lead author Mr Paul Abel, consultant urologist at Hammersmith Hospitals NHS Trust and Imperial College London. “The problem is that conventional current therapies which involve testosterone reduction can have serious side effects such as osteoporosis, which has not been fully appreciated until quite recently. This has led to reports of an increasing chance of bone fractures in these patients. Our study shows that oestrogen therapy delivered by skin patches not only controls prostate cancer, but prevents bone loss and in most cases, increases bone mass.”

Osteoporosis is a disease in which bones, particularly in the hip, spine and wrist, become fragile and more likely to break. The risk of hip fracture is serious, as it almost always requires hospitalisation and major surgery. It can impair a person's ability to walk unassisted and may cause permanent disability. Spinal or vertebral fractures also have serious consequences, including severe back pain and deformity. Once viewed primarily as a women’s disease, osteoporosis is becoming increasingly important as prostate cancer sufferers survive for longer periods of time.

The study looked at 20 men with late stage prostate cancer who were given oestrogen hormone replacement therapy skin patches, and measured bone mass using an advanced imaging technique known as x-ray bone densiometry. Average increase in bone density was over 3%, with almost all patients gaining bone density to some extent. “Patients having conventional prostate cancer treatment can lose between 2 and 10% of their bone mass alone in the first year of treatment with an increasing risk of bone fracture the longer treatment continues,” explains Mr Abel, “whereas the increase in bone mass we have seen in this trial is by contrast promising news.”

Larger trials of the HRT patch therapy for prostate cancer are planned so that long-term effectiveness and side effects of this therapy can be clarified. They will take place before this treatment is offered routinely on the NHS.

The researchers are very encouraged by the results so far, which also hold considerable promise for healthcare cost reductions. Hormone patches cost about one tenth of conventional single treatments. “There is potential for a cost saving of over US$2 billion in advanced prostate cancer treatment if this therapy is rolled out worldwide," adds Mr Abel.