Weighing the risks and benefits of HRT and making an informed decision about taking it may seem more confusing than ever. Every time another study on HRT makes it into the newspaper it seems to add to our confusion and fear. Why do the studies seem so confusing? How can we sort out the pros and cons of HRT?

A single study never absolutely proves or disproves anything by itself. What we look for is an accumulation of evidence where many different studies find the same answer. In something as complex as breast cancer it can be difficult to prove that something is a risk factor, especially if it has a relatively small effect or if it takes many years to have an impact. The most accurate type of study is what is called a prospective study. This involves following large groups of women over many years and studying differences that develop. These studies are more difficult to do and more expensive. Many studies are retrospective studies or case control studies. For example a group of women who have breast cancer are compared to a group who doesn't and retrospectively differences are analyzed based on questionnaires or registry data. The retrospective studies are more vulnerable to error.

As women our lifetime risk of breast cancer is the familiar one in eight. However, our risk is different at different ages. At age 50 there is a one in 50 chance of developing breast cancer, at age 65 it is one in 17. It is important to understand these baseline risks so that we can interpret the statistical increases reported in studies. For instance if a study reports a 40% increase in relative risk (RR 1.4) this doesn't mean there is a 40% chance that breast cancer will occur, instead it means that there is a 40 % increase over what is expected. For example in a randomly selected group of 100 women between 50-60 years old who have never taken HRT, 4 will develop breast cancer. After five years of HRT, that figure could climb to 6 women out of 100. This represents a relative risk of 40% in five years.

Two new studies comparing the risks of estrogen replacement alone with combined estrogen and progesterone therapy have added to the confusion. These studies suggested combined therapy pose a greater risk for breast cancer than estrogen alone. This proposition runs counter to previous studies that suggested the risks were similar.

The January 2000 issue of The Journal of the American Medical Association reported a retrospective study comparing the risks of breast cancer associated with postmenopausal hormone regimens. The authors reported that current and recent use of estrogen-progestin regimens increases the relative risk of breast cancer by 8% per year as opposed to a 1% per year increase with estrogen alone. The estrogen alone data did not become statistically significant until after 15 years of use. This study also found most of the increased risk with HRT was in lean women. A favorite explanation of this is because the effect of estrogen is no greater than the effect associated with increased estrogen production in overweight women.

In the February 2000 issue of the Journal of the National Cancer Institute a retrospective case control study compared hormone use in 1,897 postmenopausal women diagnosed with breast cancer and 1,637 similarly matched postmenopausal women without the disease. The authors reported a 6% increase in relative risk for every 5 years on estrogen alone and a 24% increase in relative risk for every 5 years on estrogen-progestin regimens. They further concluded that sequential combination therapy (progesterone 10-14 days per month) had a greater risk than the continuous estrogen and progestin regimen. Approximately 80% of women on combined therapy were on the sequential progestin. The difference between the sequential and continuous progestin group was not statistically significant however.

We need to look at these studies carefully before drawing a conclusion. Unfortunately, because of their designs, both fall short of proving a connection. The numbers of women who took combined HRT was small compared to the number of women, who took estrogen alone, which may have skewed the results. The intervals studied were different in the estrogen only and combined therapy groups. In addition, the type of hormones, the dose and hormone blood levels were not controlled for. Most of the women in the study took Premarin .625mg and of those that used progestin most probably used 10mg of Provera 10-14 days per month or 5mg of Provera daily. Finally there may have been errors in patient recall of what they took and other confounding variables that were not identified.

Both studies do add to a body of data suggesting that postmenopausal estrogen use for more than 5-10 years increases to some degree a woman's risk for breast cancer, and that adding progestin may increase that risk further. Remember that the vast majority of women who take HRT of all kinds do not get breast cancer.

One of our challenges in making a "hormone decision" is that we do not have all the answers we would like to have. Like so many decisions in life, we have to make the "best choice" based on what we know today while realizing that we will get new or different information over time. The decision you make should be an individual one based on your own health history, concerns and symptoms. Whatever you decide can change as new information is available or as your body and goals change.

If you decide to try hormone replacement therapy it is important to clearly identify your personal goals for its use (i.e.: reduce hot flashes, improve memory, prevent osteoporosis) and then use the lowest dose possible to achieve those goals. You should work with your doctor to develop an individualized approach and revisit the issue of what's best for you on a regular basis. If you would like to set up a consultation to discuss your personal issues of perimenopause or menopause and have a detailed evaluation and discussion please call Avenues For Health to make an appointment.