Decline in HRT Use Linked to Drop in Breast Cancer Cases

Hormone replacement therapy—HRT—has long been linked to an increase in <"">breast cancer. Now, an emerging study found that breast cancer rates declined in Canadian postmenopausal women as their HRT use declined, wrote Science Daily. The study appears online in The Journal of the National Cancer Institute.

The groundbreaking Women’s Health Initiative (WHI) trial that included over 16,000 postmenopausal women in the United States reported in 2002 that the risks of combined estrogen/progestin HRT were greater than the medication’s benefits, said Science Daily. Following this announcement, HRT prescriptions dropped significantly worldwide. The drop in prescriptions correlated to a drop in breast cancer, noted Science Daily.

Prithwish De, Ph.D., of the Canadian Cancer Society, and colleagues, looked for similar declines in Canada, reviewing Canadian registries and a national health survey for women who ranged in age from 50 to 69 years, said Science Daily. The team looked at data for HRT prescriptions, breast cancer and mammography rates, and self-reported HRT usage and found a correlation.

The “nearly 10-percent drop in invasive breast cancer rates coincided with the decline in use of hormone replacement therapy reported among Canadian women aged 50-69 years,” the team reported, quoted Science Daily. The steepest drop was seen between 2002 and 2004, when HRT use dropped from to 4.9 percent from 12.7 percent and breast cancer rates dropped to 9.6 percent; mammography rates remained unchanged during this time, explained Science Daily.

According to the researchers, the breast cancer decline “is likely explained by the concurrent decline in the use of hormone replacement therapy among Canadian women,” quoted Science Daily. The team also wrote that HRT use dropped in part due to coverage of both the WHI and the Million Women Study in the U.K.

Both studies, wrote Science Daily, indicated that breast cancer risk increased when combined HRT was used. Cancer rates in Canada saw an increase in 2005 in the 50-69 female age group, pointing to an HRT-breast cancer link, wrote the authors, said Science Daily.

“Such a rebound might be expected if occult hormone-sensitive tumors were merely slowed by the withdrawal of hormone replacement therapy rather than prevented by it. If so, hormone replacement therapy may be thought to act as a promoter, rather than a cause of breast cancer,” wrote the researchers, quoted Science Daily. “… further long-term surveillance studies of trends between hormone replacement therapy and breast cancer incidence can help reconcile the potential population-level associations of these two factors,” the team concluded.

We recently wrote that another study found that normal weight women on HRT and those who take combination estrogen/progestin therapy (EPT) over a longer time may face a higher risk of breast cancer. EPT drugs include Prempro and Premphase

The American Congress of Obstetricians and Gynecologists said that women should take the smallest dose of HRT for the shortest time frame, WebMD noted.

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