New research about breast cancer

June 1, 1998

Pharmaceutical Representative

A prescription drug that has been on the market for the past 20 years may actually prevent breast cancer, according to new research.

A prescription drug that has been on the market for the past 20 years may actually prevent breast cancer, according to new research.

In the National Cancer Institute's Breast Cancer Prevention Trial, researchers found that Nolvadex® (tamoxifen), a product manufactured and promoted by Wilmington, DE-based Zeneca Pharmaceuticals for the treatment of invasive breast cancer, reduced the incidence of breast cancer in high-risk patient populations by as much as 45%.

High-risk patients include women over the age of 60, women with a genetic history of breast cancer and women who have precancerous tissue in their breasts.

In a randomized, double-blind clinical trial that spanned the course of four years, 13,338 women in the United States and Canada received either Nolvadex or a placebo. Among those who received the brand-name product, 85 women developed invasive breast cancer; those who received a placebo, on the other hand, developed 154 cases of breast cancer.

The product works against breast cancer through its effect on estrogen in a woman's body. Estrogen promotes the growth of breast cancer cells, and the product slows or stops the effects of estrogen in breast tissue, according to the National Cancer Institute. At the same time, it does not appear to affect estrogen in other body systems.

Women who received Nolvadex did show a significantly increased risk of developing endometrial cancer, pulmonary embolism and deep-vein thrombosis. The National Cancer Institute reported that women in the cancer group developed 33 cases of endometrial cancer, vs. 14 cases in the placebo group; 17 cases of pulmonary embolism vs. 6 cases; and 30 cases of deep-vein thrombosis vs. 19 cases.

Researchers decided to stop the trial 14 months early so that women in the placebo group could benefit from the research.

Study participants will be followed by the National Surgical Adjuvant Breast and Bowel Project, the Pittsburgh-based research network that conducted the trial with the National Cancer Institute.

The Food and Drug Administration expressed support for the researchers and enthusiasm for the data results, but also issued a statement cautioning health care professionals about prescribing the product, off-label, for breast cancer prevention.

"Although tamoxifen has been approved for the treatment of breast cancer patients, FDA must first review clinical trial data before approving it for the prevention of breast cancer," Michael Friedman wrote in the FDA's official statement. "We are already in contact with the National Cancer Institute and the study sponsors to obtain the data. Once we receive it, we are committed to a thorough review within six months."

A follow-up prevention trial has already been proposed and could receive funding from the National Cancer Institute. The proposed trial would compare the results of administering 20 mg of Nolvadex versus 60 mg of Evista® (raloxifene), an antiestrogen product manufactured by Indianapolis-based Eli Lilly and Co.

Sandy Kanicki, co-chair of the Breast Cancer Prevention Trial's participant advisory board, said: "The results are so profound that I'm speechless…We have taken a major step to help women reduce their incidence of breast cancer." PR

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