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Studies Say Tamoxifen Regime Best Hope To Beat Breast Cancer

November 5, 1996

WASHINGTON (AP) _ The lifesaving benefit of taking tamoxifen to treat early breast cancer lasts for at least a decade, but only if the drug is used for five years and no longer, two studies showed.

The studies, being published Wednesday in the Journal of the National Cancer Institute, found that women who took tamoxifen for five years after early breast cancer surgery had about an 18 percent better chance of surviving without relapse than patients who did not take the drug.

One study showed that taking the drug for longer than five years conferred no survival advantage and could risk other disorders.

Experts praised the studies as providing important new insight into how to treat breast cancer at its earliest stages.

``These studies are extremely valuable,″ said Dr. Sandra M. Swain, a cancer specialist at the Comprehensive Breast Center in Washington. She said the findings now leave little question about the value of tamoxifen.

``In clinics all over the world, everyone will be using tamoxifen for five years now for sure,″ she said. ``That is of major significance.″

Tamoxifen, sold under the name Nolvadex, is prescribed as additional therapy after breast cancer surgery for women diagnosed with early stage disease. Nolvadex is made by Zeneca Inc. of Wilmington, Del.

A study by the National Surgical Adjuvant Breast and Bowel Project, a major contractor of the National Cancer Institute, gives statistical support for an NCI clinical alert issued last year that recommended tamoxifen not be used beyond five years.

That study began in 1982 and has involved more than 2,800 women.

In results published this week, the study found that women with early breast cancer, who were treated surgically and then took tamoxifen for five years, had a 12 percent better disease-free survival rate after 10 years than did women who did not take the drug after surgery.

The study found, however, that ``no additional benefit was obtained from the administration of tamoxifen beyond five years.″

It also found a slight increase in blood clots and endometrial cancer among women who continued the drug beyond five years when compared to women who stopped at five years. But specialist Swain of the Washington center suggested the numbers of these additional disorders may be too small to draw a statistically valid conclusion.

A second study, by the Swedish Breast Cancer Cooperative Group, compared the effects of the drug between two groups of women patients that took tamoxifen for either two years or five years. It measured the survival effect on both groups at 10 years after the cancer treatment started.

The study found 18 percent fewer deaths after 10 years among women who took the drug for five years after surgery compared to patients who took it for two years.

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