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Will tamoxifen lower my risk of breast cancer?

The medication may benefit some, but Dr. Judith Reichman says to assess your chance of developing the disease before taking the drug.
/ Source: TODAY

Q: I'm in my mid 40s. I've been told that I'm at high risk for breast cancer and to consider taking tamoxifen. Will taking this drug impact my chance of succumbing to this disease?

A: A new study published online in the July issue of Cancer suggests that it may not. Tamoxifen is a SERM (Selective Estrogen Recptor modulator) drug that acts as an anti-estrogen on some cells and tissues and like estrogen on others.

Tamoxifen has been successfully used to diminish the recurrence rate of breast cancer in women who have been diagnosed with and treated for the disease. In fact, tamoxifen use has been found to reduce estrogen receptor-positive breast cancer by 49 percent. The drug has also been considered useful in those women who are simply at risk for, but have not yet developed cancer. “At risk” in this case means having at least a 1.6 percent risk of developing breast cancer within five years.

Unfortunately tamoxifen isn't the easiest drug in the world to take. It can increase hot flashes and menopausal symptoms, is associated with cataracts, deep vein thrombosis, uterine cancer, and even stroke. Women who do get breast cancer despite tamoxifen therapy are more likely to develop estrogen receptor-negative breast cancer, which tends to be a more aggressive cancer and has a worse prognosis than estrogen-receptor positive cancer.

This recent publication also shows that there are no mortality benefits in “women at the lower end of the high risk” range for breast cancer. The exceptions were women who've had a hysterectomy, in which case they were not at an increased risk of developing endometrial cancer as a result of tamoxifen therapy. The study estimates that in order for tamoxifen to benefit women who haven't had a hysterectomy, their risk of breast cancer needs to be greater than 3 percent. To help you figure out what your personal risk is go to the NCI's Breast Cancer Risk Assessment Tool web site.

The study also did an interesting cost-benefit analysis of tamoxifen therapy. It found that in the U.S. the average wholesale price for tamoxifen was $1,212 a year. That works out to $1,335,690 per year of life added for women who had a 4% chance of developing breast cancer within five years (based on the calculation of all the women who would have to take the drug to achieve this affect). This cost is something you and your doctor should discuss.

Dr. Reichman’s Bottom Line: If you are told that you're at high risk for breast cancer, try to ascertain your actual percentage of risk. Tamoxifen may be of benefit, but significant health and cost issues are involved, and this medication should not be regarded as a “sure thing.”

Dr. Judith Reichman, the “Today” show's medical contributor on women's health, has practiced obstetrics and gynecology for more than 20 years. You will find many answers to your questions in her latest book, "Slow Your Clock Down: The Complete Guide to a Healthy, Younger You," which is now available in paperback. It is published by William Morrow, a division of .

PLEASE NOTE: The information in this column should not be construed as providing specific medical advice, but rather to offer readers information to better understand their lives and health. It is not intended to provide an alternative to professional treatment or to replace the services of a physician.