Study: Drop in HRT use, not mammograms, caused lower breast cancer rates
A new study in the Journal of the National Cancer Institute has found that a drop in the number of new breast cancer cases in recent years was caused by a decline in the number of women undergoing hormone replacement therapy. The study, conducted by doctors at Portland, Oregon’s Kaiser Permanente Northwest Hospital, refuted speculation that the drop may have been caused by lower numbers of women receiving mammograms.
A study by the Women’s Health Initiative released in 2002 found that women taking hormone replacement therapy were at an increased risk of breast cancer, heart disease and stroke. As a result, many women stopped receiving hormone replacement therapy because of the risk of side effects. A study published last year found that the number of new breast cancer cases fell by 7% the following year. Later reports found that the number of new cases had fallen by 11.8% the following year in women over 50.
Although researchers with the felt that the decline in the number of new breast cancer cases was caused by the fact that fewer women were using hormone replacement therapy, some doctors suggested that the drop may have been due to a drop in the number of women who were getting mammograms.
But because the more than 7,000 women involved in the Kaiser Permanente study were all receiving mammograms, doctors were able to take a better look at the effects of hormone replacement therapy on the risk of developing breast cancer. Researchers found that after 75% of their patients stopped taking hormone replacement therapy, breast cancer rates fell to their lowest levels since the mid-1980s—when hormone replacement therapy became more common. In addition, the researchers say that the majority of the change in breast cancer rates was among estrogen-receptor positive tumors—the kind that are fueled by hormone replacement therapy.