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Is Tamoxifen Safe and Effective?

Tamoxifen, otherwise known as Nolvadex, is a drug used both to prevent breast cancer and to treat it. It was developed as a birth control pill more than 20 years ago, and while it didn't really work as a contraceptive, it was shown to reduce breast-cancer rates in laboratory animals. Now it's being used to either prevent or treat breast cancer in humans. There's some controversy surrounding the safety and effectiveness of tamoxifen. The more you understand about it, the easier it will be for you to make wise health-care choices.

Simply put, tamoxifen prevents estrogen-receptor positive (ER-positive) cancer cells from taking estrogen from your body and using it. These particular cancer cells need estrogen to grow and multiply. So tamoxifen stops cancer cells from growing when the cancer is estrogen-receptor positive.

But some breast cancer is estrogen-receptor negative (ER-negative), and studies have shown there is no benefit in taking this drug if you are not past menopause or you have ER-negative cancer.

Let's look at another aspect of tamoxifen. While it blocks estrogen in breast cells, it often increases estrogen in other parts of the body. This is why tamoxifen has been associated with an increased risk for endometrial cancer. So instead of being just anti-estrogenic, tamoxifen is both anti- and pro-estrogenic! Author and naturopath Steve Austin, ND, explains that no matter what your age is, if you have ER-positive breast cancer, you are more likely to get positive results from taking tamoxifen than you would if you have ER-negative cancer. But, there is a great deal of contention over whether or not tamoxifen has any beneficial effect for cancer treatment in premenopausal women. In fact, Austin also cites a review of 28 tamoxifen studies published in the New England Journal of Medicine that reported "absolutely no improvement in survival for premenopausal women."

Side effects

Like all drugs, tamoxifen is not without its side effects. Half of all women on tamoxifen have hot flashes. Some also report vaginal dryness and discharge, menstrual irregularity, and amenorrhea (lack of menstruation). Blood clots in a small number of women have occurred, so if you have any blood-clot diseases, you won't want to use tamoxifen at all.

Even low doses may cause eye damage, much of which -- but not all -- appears to be reversed after tamoxifen is discontinued. But I would urge you to have frequent exams from your eye doctor if you take tamoxifen.

A report given at the Second Annual Lynn Sage Breast Cancer Symposium by Kathleen Pritchard, MD, stated that postmenopausal women -- especially those who are overweight -- who have been on estrogen replacement therapy and who took tamoxifen for five years have a two to four times increased risk for endometrial cancer Some information says that endometrial cancer risk doubles if you take tamoxifen for more than two years regardless of hormone therapy and weight. That news is bad enough, but studies from the Yale University School of Medicine found that women who get endometrial cancer and have taken tamoxifen have a poor prognosis.

Tamoxifen to prevent breast cancer

A study using tamoxifen in healthy women to prevent breast cancer was stopped midway due to a number of problems with the trial. Not included in the listed problems was a statement by Dr Michael DeGregorio, an oncology professor at the University of Texas. DeGregorio was concerned that women who developed breast cancer after taking tamoxifen would have tumors resistant to tamoxifen and that the drug could actually stimulate the growth of hormone-independent tumors in premenopausal women. Still, some doctors are suggesting tamoxifen to protect against breast cancer This may be one of the biggest mistakes in the area of preventive medicine.

The National Cancer Institute (NCI) published an article last November saying that healthy women over the age of 60 who take tamoxifen to protect against breast cancer are more likely to be harmed than helped. It went on to say that women under age 60 are also in jeopardy unless they have had a hysterectomy or are at a particularly high risk for getting breast cancer The National Women's Health Network -- a woman's health advocacy group -- published these findings in its January/February 2000 newsletter The conclusions made by this group, which has been persistent and vigilant in gathering news on the use of tamoxifen for healthy women, are that "only about 15 percent of women who are at least 60 years old may gain any benefit from the drug." The NCI article and the Network's response may be obtained through the Network office at 202-347-1140.

Lest you think the Network is alone in this view, a five-year, double-blind, placebo-controlled study was conducted in Italy on over 5,400 women. They found no difference between using 20 mg of tamoxifen to prevent breast cancer and using a placebo. But there was a significant increase in high triglycerides and vascular disease in the women on tamoxifen.

What about using raloxifene instead of tamoxifen? This new drug has very little risk for endometrial cancer, but when 60 mg of raloxifene was given daily for 40 months, it was shown to increase blood clots by three times. And, like tamoxifen, it didn't affect ER-negative breast cancer rates.

Simply put, tamoxifen appears to offer some benefits, but it's not without its risks. A healthy diet may do more to protect you against breast cancer And if you're considering tamoxifen as part of a cancer treatment program, consider the side effects and have regular checkups with your health practitioners to catch any side effects early, when some of them may be reversed.

Austin, Steve, ND, and Cathy Hitchcock, MSW. Breast Cancer: What you should know (but may not be told) about prevention, diagnosis, and treatment, Prima Publishing, 1994.

Pritchard, Kathleen, MD. Conference report, Second Annual Lynn Sage Breast Cancer Symposium, September 15-17, 2000.

Pearson, Cindy. "Tamoxifen for healthy women: risk reduction for whom?" The Network News, January/February 2000.

Narod, Steven A., et al. "Tamoxifen and risk of contralateral breast cancer in BRCA1 and BRCA2 mutation carriers: a case-control study," The Lancet, vol. 356, December 2, 2000.

Senior, Kathryn. "Is ralixifene set to rival tamoxifen?" The Lancet, vol. 353, June 19,1999.

Veronesi, U., et al. "Prevention of breast cancer with tamoxifen: preliminary findings from the Italian randomised trial among hysterectomised women," The Lancet, vol. 352, July 11, 1988.

Pearson, Cynthia. "Congress holds hearing on tamoxifen trial," The Network News, January/February 1993.

Tamoxifen Checklist

[check] If you take tamoxifen, it may work best if you take it for only two to five years.

[check] See an ophthalmologist regularly.

[check] If you're premenopausal, hormonal contraceptives may interact with tamoxifen. Don't use both.

[check] If you're premenopausal and take tamoxifen, use another method of birth control. Tamoxifen may have negative effects on the baby.

[check] Don't take tamoxifen if you have a history of blood clots.

From Austin & Hitchcock

A study published in The Lancet last December does indicate that tamoxifen cuts the risk for breast cancer in women with mutations in BRCA1 or BRCA2 genes. What this means is that if you have a history of breast cancer in your family and have either of these genes, you may be able to prevent breast cancer by using tamoxifen.
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Article Details
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Title Annotation:for breast cancer treatment and prevention
Author:Fuchs, Nan Kathryn
Publication:Women's Health Letter
Article Type:Product/Service Evaluation
Geographic Code:1USA
Date:Apr 1, 2001
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