A recent article by one of my favorite health writers for the New York Times, Tara Parker-Pope, questioned the decision of millions of women not to take the drug tamoxifen to lower their odds of developing breast cancer. I was stunned by her conclusions. I always thought these women were making a wise and reasonable choice based on the evidence and I strongly disagreed with her conclusions.

First a little background. Tamoxifen, along with Evista or raloxifene, are referred to as selective estrogen receptor modulators (SERMs). This means they block the action of estrogen on some tissues such as the breast (which lowers breast cancer risk) and act like estrogen on other tissues such as the bones (which means less bone loss). But their good effects need to be viewed in the context of their many and potentially life-threatening side effects.  More about these worrisome effects later.

Tamoxifen has been shown to reduce the risk of breast cancer by half in women who are at a higher than average risk . Risk factors considered include the following:  age 40 years or older and have a mother or sister or daughter with breast cancer, a history of atypical cells on breast biopsy, early onset of puberty and a first pregnancy after age 30.

To learn more about your risk for breast cancer using the popular although not precise Breast Cancer Risk Assessment Tool you can go to www.cancer.gov/bcrisktool/.  A risk score of 1.7 or higher is arbitrarily defined as high risk. This means that 17 out of every 1000 women with similar circumstances or risk factors would develop breast cancer over the next five years. Taking tamoxifen would reduce this risk in half – meaning about 8 or 9 fewer breast cancers would be diagnosed during that period of time. The tool can’t say precisely which of the women would benefit from taking tamoxifen however.

For years both tamoxifen (and more recently raloxifene) has been approved for use in higher risk women to prevent breast cancer. Yet despite many doctors encouraging women to take it, very few women actually do. However it is reasonably taken by thousands of women who already have a type of breast cancer that contains estrogen receptors. For these women, it reduces the chance of a second breast cancer or the original breast cancer coming back. But even for these women with cancer, they are advised to take tamoxifen for only five years because the risk of a totally new cancer increases beyond this point.

Researchers at the University of Michigan questioned why so many women declined to take tamoxifen to prevent breast cancer and sought to find out why. They studied 632 women who were candidates for tamoxifen to prevent breast cancer. A comprehensive computer based program was developed that educated these women about the benefits and risks of taking tamoxifen. They laid out the numbers in very precise terms.

For example, of a hypothetical group of 1000 woman who were 52 years old and who met the criteria for increased risk, 9 would avoid breast cancer and 13 would avoid a broken bone. But here is the rub: the drug would cause 21 cases of endometrial (uterine lining) cancer which requires at a minimum a complete hysterectomy, 21 would develop blood clots which require prolonged and potentially risky anticoagulant therapy and which could potentially travel to the lung and be fatal, 31 would develop cataracts from the drug, and 12 would develop sexual problems. Finally the drug would also cause about 120 women who were not yet in menopause to develop symptoms including hot flashes, vaginal complaints from dry and thin vaginal tissues from the lack of estrogen, and possibly irregular periods. What is not mentioned was the potential number of lives lost versus the number of lives saved from the tamoxifen treatment. By my calculation, more lives could be lost from the side effects of the drug than could be saved by its’ benefits. As feared and serious as breast cancer is, most women don’t die from their breast cancer.

Dr. Angela Fagerlin, an internist at the University of Michigan, noted, “When the numbers were laid out for them in a way they could clearly understand, they weren’t interested in taking tamoxifen.” According to Tara Parker-Pope, Dr. Fagerlin conducted a similar study using reloxifene, which has fewer side effects, and the results were similar.

Ms. Pope seemed to think that these women were not making a wise decision. She noted that some women said they simply did not want to take a pill every day. I strongly doubt that taking a daily pill was the deciding issue. Women are wiser than that and many women will do almost anything that reasonably assures them good health. She went on to comment that millions of women will take a daily pill however for birth control (the benefits of the pill for most women far exceed the small risk) and many more will take a daily vitamin (there is virtually no risk and for women in child-bearing years, there is great benefit because of the added folic acid which helps prevent early fetal development problems).

In the final analysis, it seems that women really do know best when it comes to making wise health decisions. Obviously women for years have chosen not to take tamoxifen to prevent breast cancer because they feared the risks far outweighed the benefits. Now a study convincingly shows that even when the risk and benefits were spelled out in more precise numerical terms, women at high risk remain opposed to taking this drug. Given the extraordinary amount of risk associated with the drug, it seems their decision is wise.

How do primary care doctors view a healthy woman’s decision to avoid tamoxifen to prevent breast cancer? My guess is that they too have agreed with women and their choice not to take tamoxifen. After all, it is a woman’s primary care physician (either internist, family doctor or gynecologist) who will help a woman identify her risk of cancer in the first place and advise her about the pros and cons of treatment. A doctor’s advice to a patient is often cited as the single most important reason a patient will initiate a test or treatment. So I do believe that primary cancers wisely view the risks far outweighing the benefits too and probably do not encourage their patients from taking the drug. On the other hand, primary care doctors are often too busy to do a formal risk assessment for breast cancer in women and the topic of tamoxifen may never come up.

I believe we need to continue to develop tools that will give all patients as detailed, useful and personalized information as possible about the health and treatment decisions they are making. I suspect that more often than not, patients will make the right decision for them. And perhaps more often than we would like, this decision may not agree with ours. We need to trust that patients really do know best.

I am reminded of the words of the missionary physician, Dr. Albert Schweitzer, who understood the power of a patient’s own health radar when he told his fellow physicians:

“Each patient carries his own doctor inside him.
They come to us not knowing that truth.
We are at our best when we give the doctor who resides within each patient a chance to go to work.”

For me, I am resolving for 2010 to get better at giving patients the information they need to make good health decisions in clear and accurate
language.  I will trust that most patients will make the best decisions in the end.  What are your New Year’s resolutions?

I wish all of you a happy holiday season and a wonderful new year.

As always, I welcome your thoughts and suggestions.

Warm regards,

Dr. Marie
Marie Savard, M.D.
ABC News Medical Contributor
Author of Ask Dr. Marie: Straight Talk and Reassuring Answers to You Most Private Questions




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