Watch out for breast tenderness if you're taking HRT

The history of hormone replacement therapy (HRT) goes back further than you might think. A book called The Estrogen Elixir, by Elizabeth Siegel Watkins, describes early experiments performed at a kitchen table in St. Louis by biochemist Edgar Allen, using pig ovaries from a local meat-packing plant. Allen's work led to the discovery of estrogen in 1929. Many years later, a leading brand of estrogen would become the best-selling prescription drug in the United States.

Things have changed a lot over the past few years, and HRT is now linked to some serious side effects, including a higher risk of breast cancer. While the FDA says that HRT can still be used to treat symptoms of menopause, it recommends using the lowest dose that works, and for the shortest possible time.

Unfortunately, it's not always obvious which women have the highest risk of side effects (although the risks tend to increase as you get older). For women facing unpleasant symptoms such as hot flashes, the decision about whether to use HRT can be difficult.

A new study of more than 16,000 women has shed some more light on the topic. Researchers had wondered whether getting breast tenderness during treatment with HRT might be a warning sign of breast cancer. Their theory proved correct.

In the trial, 2.9 in 100 women who developed breast tenderness while taking HRT went on to get breast cancer in the next five years or so. Women who didn't get breast tenderness had a 2.2 in 100 risk of cancer.

While the difference is fairly small, and it's obvious from the figures that not all women with breast tenderness go on to get cancer, it's a good idea to tell your doctor if you start to get breast tenderness while taking HRT. Your doctor can help you decide whether or not to continue with treatment.

The type of HRT used in the study contained estrogen made from the urine of pregnant horses and another hormone called progestin. We don't know whether the results apply to other kinds of HRT.

What you need to know. HRT increases the risk of serious side effects, although for most women, the risk is small. If you're thinking of taking HRT, get all the information you can, and weigh the pros and cons with your doctor.

—Philip Wilson, patient editor, BMJ Group

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