estrogen estrogen

Herceptin has proved to be effective in prolonging the lives of the 12 percent of women with breast cancer whose malignancy hasn't spread to other organs, and whose cancer is HER2-positive. But side effects can be a problem. Jeff J Mitchell/Getty Images hide caption

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Jeff J Mitchell/Getty Images

Hormones clearly influence a women's health, but figuring out how is a tricky business. Andrew Ostrovsky/ hide caption

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Andrew Ostrovsky/