Additional Data Strengthens Link Between Hormone Use and Breast Cancer

Additional Data Strengthens Link Between Hormone Use and Breast Cancer

According to results recently published in the New England Journal of Medicine, additional data has strengthened the link between the use of hormone therapy and an increased risk in breast cancer among postmenopausal women.

As women reach menopause and beyond, more than 80% will experience symptoms such as hot flashes, night sweats, sleep disturbance, and vaginal dryness. Many women who are suffering from these postmenopausal symptoms take hormone therapy, which may consist of estrogen only or estrogen plus progestin. However, results from recent studies have raised concerns about the health effects of postmenopausal hormone therapy.

This recent information about the potential health risks of postmenopausal hormone therapy came from large clinical trials conducted as part of the Women’s Health Initiative (WHI). After the first WHI results were released in 2002, there was a rapid decline in the use of postmenopausal hormone therapy.

A possible link between this decline in use of postmenopausal hormone therapy and a drop in breast cancer incidence was suggested by evaluation of a large U.S. cancer registry. Between 1990 and 1998, the rate of breast cancer increased by 1.7% each year. After 1998 breast cancer rates began to decline by 1% each year. In 2003, however, there was a sharp 7% drop in the rate of breast cancer.

Overall in 2003 there was an 8% decline in the rates of estrogen receptor (ER)-positive breast cancer and a 4% decline in the incidence of ER-negative breast cancer. Among women aged 50 to 69 years, the incidence of ER-positive breast cancers decreased by 12% and the incidence of ER-negative breast cancer decreased by 4%.

Data from 2004 regarding incidence of breast cancer has recently been evaluated, further substantiating the link between the decline in use of hormone therapy and a decreased incidence of breast cancer.

• Data from 2004 demonstrated little decrease in breast cancer incidence compared to 2003. As well, use of hormone therapy remained fairly constant between 2003 and 2004.

• The decrease in breast cancer from 2001 to 2004 was 8.6%. This decrease was found only in women who were 50 years of age or older and was more evident among hormone-positive breast cancer compared with hormone-negative breast cancer.

The researchers concluded that these data provide additional support indicating a link between hormone therapy and breast cancer among postmenopausal women. They state, “The decrease in breast cancer incidence seems to be temporarily related to the first report of the Women’s Health Initiative and the ensuing drop in the use of hormone-replacement therapy among postmenopausal women in the United States. The contributions of other causes to the change in incidence seem less likely to have played a major role, but have not been excluded.”

Postmenopausal women who are experiencing menopausal symptoms may wish to speak with their physician regarding their individual risks and benefits of hormone therapy.

Reference: Ravdin P, Cronin K, Howlader N, et al. The Decrease in breast cancer incidence in 2003 in the United States. The New England Journal of Medicine. 2007; 356:1670-1674.

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