MEDICATIONS: STUDY IDENTIFIES WOMEN MOST LIKELY TO BENEFIT FROM TAMOXIFEN TO PREVENT BREAST CANCER

Sept. 1, 2004 — Tamoxifen for the prevention of breast cancer appears to be most cost-effective for a specific subset of women — namely women ages 40 to 50 who are at a significant risk for the disease, according to a new analysis in the September issue of Obstetrics & Gynecology. Tamoxifen is cost-effective for women between the ages of 40 and 50 who have at least a 3.4 percent five-year risk of breast cancer. However, it isn't cost effective for women ages 60 to 65 unless their five-year risk is very high (more than 5 percent).

Tamoxifen is the only drug that is FDA-approved for the primary prevention of breast cancer in women. However, it has side effects such as the risk of stroke, endometrial cancer, deep vein thrombosis, and pulmonary embolism. Past studies have been unclear in identifying women who would most benefit from tamoxifen.

Researchers from the University of North Carolina at Chapel Hill performed a cost effectiveness analysis to determine which women would benefit most from taking tamoxifen. They point to an earlier report that more than 10 million US women are candidates for tamoxifen and at least two million of these would experience a net benefit from the drug.

Their analysis concludes the following:

· Tamoxifen is cost-effective for every woman between the ages of 40 and 50 with at least a 3.4 percent five-year risk of breast cancer.

· For women 40 years of age, tamoxifen can be justified with a baseline five-year risk as low as 1.5 percent.

· For women ages 60 to 65, tamoxifen would only be cost-effective if the five-year risk of breast cancer is very high (more than 5 percent).

· For women ages 51 to 59, tamoxifen treatment decisions need to be individualized according to actual age, whether or not a woman has had a hysterectomy, and whether their five-year risk of breast cancer is at least 3.5 to 4 percent.

· For women with a high risk of cerebral vascular disease (eg, known atherosclerosis, strong family history of stroke) or a hypercoagulable state, tamoxifen is contraindicated.

Physicians can quickly calculate a woman's five-year risk of breast cancer by using The Gail Model, a formula that incorporates current age, age at menarche, age at birth of first child, race, breast biopsy history, and family history of breast cancer.