Tamoxifen Beyond Five Years; No Added Benefit

The life-saving benefits of Zeneca's Nolvadex (tamoxifen) in the treatment of early breast cancer last for at least a decade, even if the drug is given for only five years, according to two studies which have now been published in the latest issue of the Journal of the National Cancer Institute.

The studies, by the National Surgical Adjuvant Breast and Bowel Project (a major contractor of the US National Cancer Institute), were first publicized last year (Marketletter December 11, 1995). The benefits of the drug are not in doubt; women who took Nolvadex for five years after surgery for early-stage breast cancer had about an 18% better chance of survival without relapse than those who did not receive the drug. A second study by the Swedish Breast Cancer Cooperative Group measured the effects of two versus five years of tamoxifen treatment after 10 years, and found an 18% survival advantage in the five-year group.

However, data from the first study suggests that taking tamoxifen for longer than five years offered no survival advantage, and was associated with increases in other disorders, such as thrombosis and endometrial cancer. But some investigators have played down the findings. Sandra Swain of the Comprehensive Breast Center in Washington said the number of these additional disorders may be too small to draw a statistically valid conclusion.