Breast cancer's sudden decrease in several countries can be credited to a 2002 federal warning against overuse of hormone-replacement drugs after menopause, a new study argued. The findings, published Wednesday in the New England Journal of Medicine, were disputed by a hormone-pill maker and others, adding to the debate over the safety of such treatment. Before 2002, about 210,000 U.S. women each year were diagnosed with breast cancer, according to federal statistics. After 2002, the rate suddenly dropped to below 190,000 each year and has stayed there through 2005, the latest year in which figures are available. Other countries also registered drops.
In 2002, the National Institutes of Health halted a large study of Wyeth's drug Prempro and warned that the treatment, a combination of the hormones estrogen and progestin, increased breast cancer, heart attacks and strokes. Another study found Prempro also increases dementia in elderly women. Both findings were part of research launched by the Women's Health Initiative. In the new analysis, researchers from the WHI re-examined the medical records of the 16,608 women in the study, both before and after 2002. Half of the women had been randomly assigned to take Prempro until 2002. The new analysis found that Prempro's added breast-cancer risk fell quickly, within about two years, after women stopped taking hormone therapy. That's similar to what was observed in the overall U.S. population.