Researchers are linking a dramatic drop in the number of breast cancer cases to the decline in estrogen consumption by menopausal women. Women dropped hormone replacement therapy en mass after a 2002 study tied it to breast cancer risk. Other scientists argued that the decline—about 16,000 fewer new cases per year—may have other causes.
"This is colossal," said Rowan Chlebowski of Harbor-UCLA Medical Center. "It translates into thousands of fewer breast cancers." The theory is that the hormones may essentially throw gas on the fire of estrogen-related tumors. Without the treatment, they may never grow. A similar study in the U.K. recently linked hormone therapy to ovarian cancer.