Study: 2.4 Million Women Would Benefit From Taking Tamoxifen

More than 2.4 million mostly white American women who do not have breast cancer would likely benefit from taking tamoxifen to prevent the disease, according to a study reported in the April 2 issue of the Journal of the National Cancer Institute.

But researchers caution that the choice to use the drug, which halves the incidence of breast cancer in women most likely to develop the disease, is an individual one that should be made in consultation with one's physician.

Many women who have had breast cancer are given tamoxifen to prevent a recurrence of the disease, but researchers said they do not know how many higher-risk women currently take the drug as a preventative.

But researchers estimated if all women who could likely benefit from taking tamoxifen as a preventative were doing so, almost 30,000 cancers might be prevented over the next five years.

In their study, researcher Andrew N. Freedman and his colleagues at the National Cancer Institute (NCI) weighed the risk of side effects associated with tamoxifen against its benefits to determine how many women in the United States would likely derive a net benefit from the drug.

The researchers estimated that 10 million American women between the ages of 35 to 79 years old might benefit from taking tamoxifen strictly from a standpoint of preventing breast cancer.

But side effects of the drug include endometrial cancer, stroke, deep vein thrombosis and pulmonary embolism, and older women are especially at risk for these side effects.

Because younger women are less likely to experience the drug's adverse affects, the researchers concluded that the highest percentage of women likely to derive a net benefit from tamoxifen are between the ages of 40 to 59. They ultimately put the number who would derive a net benefit at 2.4 million white women and 43,000 black women.

"Although these findings suggest a benefit for tamoxifen for certain women, the choice to take tamoxifen is an individual one," said Freedman. "Women with increased risk of breast cancer must carefully consider the benefits and risks in consultation with their physicians."

Other sources: National Cancer Institute