Millions of women stopped taking hormone pills consisting of estrogen and progestin, which were meant to relieve symptoms of menopause, when a study linked hormone replacement therapy to a higher risk of breast cancer, heart disease, and other health problems.
The full effect of hormone replacement therapy was not known. However, the incidence of breast cancer had been increasing before 2002.
Nearly thirty percent of women over the age of fifty were taking the hormones and about half became alarmed and discontinued their use once the study was released. Only women suffering from the most debilitating symptoms of menopause felt it was worth the risk to continue taking them.
A new analysis of federal cancer statistics shows a substantial drop in breast cancer rates in the United States in 2003, and researchers believed that women’s reaction to the study is the cause.
“It is the largest single drop in breast cancer incidence within a single year I am aware of,” said Dr. Peter Ravdin, a research professor in the Department of Biostatistics at the University of Texas MD Anderson Cancer Center, where the analysis was conducted.
“Something went right in 2003, and it seems that it was the decrease in the use of hormone therapy, but from the data we used we can only indirectly infer that is the case,” he said in a statement.
Doctors believe that small tumors that had been growing became undetectable on mammograms after the flow of hormones stopped entering the body.
Statistics tend to support the theory since the most dramatic drop occurred in a group of women between the ages of fifty to sixty-nine with estrogen receptor positive breast cancer. Estrogen has been known to feed these types of tumors.
Although researchers believe they are on the right track, more statistics are needed to confirm what the studies so far have shown.