A Washington Post front-page story points to a new analysis published today in the New England Journal of Medicine that reaffirms the theory that the recent decline in the number of breast cancer cases is due to the reduction in hormone use by menopausal women. From the WP:

The statistics show that the number of breast cancer cases being diagnosed began falling abruptly after concerns emerged about the safety of hormone treatment and that the decrease persisted into the following year, strengthening the case that the trends are related, researchers said. […]

The new analysis showed that the breast cancer rate began falling almost immediately after the Women’s Health Initiative findings were released in July 2002, dropping 6.7 percent between 2002 and 2003. The 2004 data showed that the rate remained at the lower level, having fallen 8.6 percent between 2001 and 2004.

The researchers said that indicates the drop was primarily caused by the decrease in hormone use and not other factors, such as fewer women having mammograms, greater use of hormone-blocking drugs such as tamoxifen or an unknown change in the environment, and that it will be long-lasting.

“The fact that the incidence rate did not go back up suggests that the effects will be long-lived,” said Peter Ravdin of the University of Texas, who helped conduct the analysis.

The link is strengthened by the fact that the decline occurred primarily in women ages 50 to 69, the age group most likely to use hormones, and predominantly in a form of breast cancer sensitive to estrogen. New cases of this type fell 14.7 percent, the researchers said.

The story also notes that Wyeth Pharmaceuticals, which makes the most widely prescribed hormones, questions the link.

The New England Journal of Medicine study is online. More information about the Women’s Health Initiative is available here.

As before, the Wall Street Journal and The New York Times offered different takes on the study. Under the headline “Breast-Cancer Data Pose Puzzle,” Tara Parker-Pope’s story begins: “A new report shows breast-cancer incidence remains at its lowest rate in 20 years, but it raises more questions than it answers about why an estimated 16,000 fewer women in the U.S. have been diagnosed with the disease.”

The NYT story, “Sharp Drop in Rates of Breast Cancer Holds,” by Gina Kolata, takes a less-skeptical approach.

Plus: This Associated Press story (via the Washington Post) covers the hormone study published in NEJM and also cites a study of nearly 1 million women in the UK that showed “those who took hormones after menopause were 20 percent more likely to develop ovarian cancer or die from it than women who never took the pills.” The study was published online by the London-based journal The Lancet. The full text of the analysis is free, but registration is required.

As the AP notes: “For consumers, the new research doesn’t change the advice to use the lowest dose for the shortest time possible for hot flashes and other menopause symptoms that can’t otherwise be controlled.”

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