Breast cancer risk tied to HRT evident across race
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Postmenopausal hormone therapy with estrogen or estrogen-progestin is associated with an increase in breast cancer risk across ethnic groups, new research indicates.
Previous studies have indicated that menopausal estrogen-progestin therapy increases the risk of breast cancer, but it is unclear whether this association varies by specific prognostic factors and ethnicity.
“Findings from our study are consistent with previous literature of an association between hormone therapy use in breast cancer, in particular, an increase in risk associated with current estrogen-progestin therapy use,” Dr. Malcolm Pike from the University of Southern California, Los Angeles, and colleagues write in the International Journal of Cancer.
Moreover, “our study provides some of the first results comparing breast cancer risk among different ethnic groups in relation to hormone therapy use. The results suggest that risk among women of other races is similar to the risk previously reported among Whites,” they note.
Their findings are based on data from the Multiethnic Cohort Study of more than 55,000 women to investigate the relationship between menopausal hormone therapy use and breast cancer risk.
Current use of estrogen-progestin increased the risk of breast cancer an estimated 29 percent per 5 years of use, the authors report. Current use of estrogen was associated with a 10 percent increased risk of breast cancer per 5 years of use.
The increased risk associated with current estrogen-progestin use was observed in all ethnic groups, the results indicate, but the increased risk associated with current estrogen use was not apparent among African-American women.
Past estrogen-progestin use was associated with a significant increase in breast cancer risk only among African-American women, the researchers note. Past estrogen use was not associated with a significant increase in breast cancer risk in any ethnic group.
The breast-cancer risks associated with current estrogen-progestin and estrogen use were greater for women with body mass indices below 25, the report indicates, but increased risk was also noted in women with higher BMIs.
Estrogen-progestin use was associated with a clear increase in risk for advanced disease, the investigators say, and both estrogen-progestin use and estrogen use were significantly associated with estrogen receptor-positive tumors.
SOURCE: International Journal of Cancer, March 1, 2006.
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