DALLAS: The sharp drop in breast cancer cases reported in 2003 in the United States could be on account of several millions of older women stopping the use of hormone replacement therapy, say researchers.
Studies at the University of Texas had found that there had been a 7 per cent drop in new breast cancers in the U.S. during that year. Researchers involved in the study say this could be directly linked to women giving up HRT because of adverse reports of its efficacy and safety.
The researchers at the University of Texas M.D. Anderson Cancer Center said they found a decline of 12 per cent in women in the age group of 50-69, who were diagnosed with estrogen receptor positive breast cancer.
The researchers, presenting their findings at the San Antonio Breast Cancer Symposium, said around 14,000 fewer U.S. women were diagnosed with breast cancer in 2003, compared with the previous year. Incidentally, a large study of women using HRT was stopped after evidence came up suggesting therapy using HRT increased the risk of developing breast cancer. The researchers said the number of women in the country using HRT had halved by the end of 2002 following this finding.
The team felt the decline could be explained by existing tumors stopping growing, shrinking or disappearing.
The researchers, however, clarified that their analysis is based on population statistics and hence the reasons are not completely certain.
Peter Ravdin, a research professor in the department of biostatistics at M. D. Anderson Cancer Center, says this is possibly the largest single drop in breast cancer incidence within a single year. "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.
The scientists had analyzed data from nine regions across the country that contribute data to the NCI's Surveillance Epidemiology and End Results (SEER) database, from which national cancer incidence statistics are derived.
HRT ensure supply of the hormone estrogen and sometimes progestin to women after menopause.
