For the past decade, women have been cautioned about using hormone replacement therapy (estrogen and/or progestin) to combat the symptoms of menopause. Karla Kerlikowske of the University of California, San Francisco and her colleagues wondered what effect that advice has had on cancer rates. Their conclusion: cancer rates have dropped due to the cessation of hormone replacement therapy.
The scientists examined the mammography records of nearly 700,000 women, aged 40 to 79, over a ten-year period from 1997 to 2007. The first large studies showing the risks of hormone replacement were done in 2002, resulting in an immediate and precipitous decrease in the number of women using the hormones. Among women who were old enough to have started using hormone therapy prior to 2002 (aged 50 to 69), the breast cancer rate dropped by over 20% between 2002 and 2005. This strongly suggests that the cessation of hormone replacement therapy was responsible for the decrease in cancer.
Although it seems clear that hormone replacement therapy should be avoided if possible, I’d like to put the actual risks in perspective. Even in 2002, the peak of hormone usage, there were only 40 cases of breast cancer out of every 10,000 women in the study. In other words, stopping the hormone treatment dropped each woman’s risk of cancer from about 0.4% to about 0.3%. While this reduction is a worthy goal, those who need hormone replacement should not panic.