(July 10, 2008 - Insidermedicine) The increased risk of gallbladder disease among postmenopausal women taking hormone replacement therapy can be reduced if the medication is taken via transdermal form, according to research published in the British Medical Journal.

Here are some facts about HRT:

•    It remains the most effective treatment for hot flashes and night sweats associated with menopause.

•    Disadvantages include a small increase in the risk of heart disease, stroke, breast cancer, and blood clots.

•    Benefits include a reduced risk for osteoporosis and colorectal cancer.

Using data from the Million Women Study, researchers from the University of Oxford examined the link between HRT and gallbladder disease. Nearly 20,000 women were admitted to hospital with gallbladder disease and over 17,000 underwent surgery to remove their gallbladder.

Over five years, hospital admission rates per 100 women to remove the gallbladder was 1.1 for those who had never taken HRT, 1.3 for those taking HRT via transdermal application, and 2.0 for those taking HRT in pill form. Ten years after stopping HRT, gallbladder disease remained higher than for women who had never taken HRT.

We had a chance to speak with Dr. Bette Liu, from Oxford's Cancer Epidemiology Unit, who offered some further insight for patients.

Today’s research demonstrates that by choosing to use HRT in transdermal rather than pill format, one woman would be spared gallbladder surgery for every 140 women who took the medication over five years.

For Insidermedicine in Depth, I'm Dr. Susan Sharma.