Hormone Replacement Therapy And Breast Cancer Risks

I have been taking HRT (Prempro) for 13 years and am concerned about breast cancer. I have no family history, but have recently had a small cyst in my left breast. I am considering taking Evista. How can I decide what is best?

There has been considerable controversy around the question of hormone replacement therapy (HRT) for women after menopause, particularly since some studies have shown that there is a small increase in the risk of breast cancer in women taking HRT, understandably a frightening possibility, especially in someone with a strong family history of the disease. Publication of a recent study on that risk, and the development of designer anti-estrogens such as tamoxifen and raloxifene have changed our perceptions of this risk, and have expanded the possible approaches to this question.

I presume that today’s writer has not had a hysterectomy, since she is taking Prempro, a combination of standard dosages of two hormones, Premarin, an estrogen, and Provera, a progesterone. Women who have had hysterectomies do not need to take HRT containing progesterone, which is given solely to prevent the development of cancer of the endometrium, the lining of the uterus.

For many years it has been assumed that the possibility of increased risk of developing breast cancer due to HRT was due to the estrogen component, not the progesterone. A recent study, however, has turned this around, and demonstrated that most of the risk, about 80 percent of it, was related to the progesterone, and only about 20 percent was due to the estrogen. This means that for women able to take HRT containing only estrogen, the additional risk of breast cancer is very small. It has also been shown in previous studies that the type of breast cancer which develops in postmenopausal women taking HRT is non-aggressive, and more easily cured than most breast cancers.

The benefits of taking estrogen after menopause are many. It has definitely been shown to reduce the chances of developing osteoporosis. I believe that it also reduces the risk of arteriosclerotic heart disease, which kills many more women than does breast cancer, although some recent studies have had results indicating that it may not be as protective as we had assumed. It reduces the risk of strokes, and probably reduces the risk of developing Alzheimer’s disease. It stops the hot flashes that many women find so troubling, and maintains the normal soft membranes in a woman’s genital area and urethra. Therefore many doctors, myself included, have tended to advise HRT for most women, after going through the various risks and benefits and helping them to make an informed decision.

Now, with the development of raloxifene (Evista), women have another, very exciting option. Raloxifene is a selective anti-estrogen, meaning that it counteracts the effects of estrogen on some organs, but imitates the effect on others. Both it and tamoxifen counteract the effect of estrogen on the breast; in fact tamoxifen is commonly used as a treatment for breast cancer, and it reduces the chances of a woman developing breast cancer in the first place. Raloxifene has the same anti-estrogen effect on the breast, but it mimics the effect of estrogen on the bones — reducing osteoporosis; and probably on the heart — reducing the risk of heart attacks. It does not stimulate the development of endometrial cancer. The answer to whether it will also reduce the chances of someone developing Alzheimer’s must await the completion of further studies.

What raloxifene does not do is suppress the hot flashes, and maintain the membranes of the genitals. But many women never get bad hot flashes, or quickly get over them, and the maintenance of genital membranes may not be too important to them. For a woman in this situation, raloxifene may be almost the perfect choice. A reduced risk of breast cancer, reduced osteoporosis, reduced heart disease, less risk of endometrial cancer and maybe a reduced risk of Alzheimer’s disease are great benefits. We don’t know if today’s writer had bad hot flashes, or if the thinning of the membranes in her genitals would be a problem, but these are certainly issues that she could discuss with her doctor along with the benefits in coming to an informed choice about Evista.

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