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University of Iowa News Release

Release: April 4, 2003

NCI Study Estimates Women Could Benefit From Tamoxifen

More than 10 million women in the United States have a high enough risk of developing breast cancer that they could consider taking the breast cancer chemoprevention drug tamoxifen, according to the National Cancer Institute (NCI).

When the scientists examined this group of women using a risk-benefit analysis of the drug, they found that more than two million women would be likely to derive overall benefit from the drug without undue risks. The results appeared in the April 2 issue of the Journal of the National Cancer Institute.

In terms of preventing actual breast cancers, the researchers estimated that among the 2.4 million white women who could likely benefit overall from taking tamoxifen, 58,148 breast cancers would develop over the next five years. But, if all these women took the drug for that length of time and experienced the typical 49 percent reduction in breast cancer, 28,492 cases could be prevented or deferred.

When analyzed by race, 18.7 percent of white women ages 35 to 79 in the United States, or 9.4 million, would be eligible for tamoxifen, but only 4.9 percent, or 2.4 million, are likely to benefit from the drug. About 6 percent of U.S. black women in the same age range, or 430,000, would have a high enough risk to take the drug, but only 0.6 percent, or 43,000, would likely derive a net benefit from it. The rates are lower for black women than white women because the overall risk for breast cancer in black women is lower and because the rates of stroke, deep vein thrombosis and pulmonary embolism are higher than among white women.

Tamoxifen was approved five years ago as the first drug to prevent breast cancer. It can halve the incidence of breast cancer in women who are most likely to develop the disease. As with all medicines, tamoxifen has side effects that may affect some women and not others. In this case, the effects are rare but serious - endometrial cancer, stroke, deep vein thrombosis and pulmonary embolism.

In an attempt to avoid the potential risk of those side effects, the NCI began a follow-up study, the Study of Tamoxifen and Raloxifene (STAR). Women who access can learn more about the study. STAR will compare the proven benefits of tamoxifen to the promising effects of raloxifene in postmenopausal women at increased risk for breast cancer. Preliminary data from osteoporosis studies show that raloxifene has the potential to reduce a postmenopausal woman's risk for breast cancer, yet that observation has yet to be proven through a clinical trial. The FDA has already approved raloxifene to treat and prevent osteoporosis.

STAR is one of the largest breast cancer studies ever conducted, and will enroll more than 22,000 postmenopausal women at more than 500 sites in the United States, Puerto Rico and Canada. To date, more than 14,000 women are participating in STAR. Women in the study take either tamoxifen or raloxifene daily for five years and receive close follow-up examinations. AstraZeneca Pharmaceuticals of Wilmington, Del., the maker of tamoxifen, and Eli Lilly and Company of Indianapolis, Ind., the maker of raloxifene, are providing the medications at no cost to the participants.

In addition to visiting the Web site, postmenopausal women with an increased risk for developing breast cancer in Iowa and western Illinois can contact Mary Fitzgerald, study coordinator, at (319) 356-2778 or toll free (800) 237-1225 or the NCI's Cancer Information Service toll free at (800) 422-6237, for more information about STAR. Further information on the risks and benefits of taking tamoxifen for breast cancer chemoprevention can be obtained at NCI's Web site

University of Iowa Health Care describes the partnership between the UI Roy J. and Lucille A. Carver College of Medicine and UI Hospitals and Clinics and the patient care, medical education and research programs and services they provide. Visit UI Health Care online at

STORY SOURCE: Joint Office for Planning, Marketing and Communications, University of Iowa Health Care, 200 Hawkins Drive, Room 8798 JPP, Iowa City, Iowa 52242-1009.

CONTACT: Tom Moore, 319-356-3945,
Writer: Tom Moore.