Study casts more doubt on mammography effectiveness

It is a debate that just won't disappear.

The latest volley in the argument over the efficacy of mammography was fired Tuesday in an article in the British Medical Journal in which researchers reported that the results from a quarter-century long study involving 90,000 women cast doubt on the value of the screening test for women of any age.

According to the researchers, led by Anthony Miller of the University of Toronto, death rates from breast cancer were similar in women who underwent mammograms and those who didn't.

Furthermore, the researchers determined, one in five cancers found with mammography and treated wouldn't have threatened the women's health and didn't need to be treated via methods such as radiation, chemotherapy, or surgery.

The study is bound to rekindle the debate between those who believe regular mammography saves lives and those who believe the evidence suggests otherwise.

"It will make women uncomfortable, and they should be uncomfortable," Russell Harris, a screening expert and professor of medicine at the University of North Carolina, Chapel Hill, who was not involved in the study, told the New York Times. "The decision to have a mammogram should not be a slam dunk."

In this large study of 90,000 Canadian women, half randomly underwent annual mammograms along with yearly physical breast examinations for five years, while the other half received only physical examinations along with regular medical care. After 20 years, 3,520 women in the mammography group and 3,133 in the control group had been diagnosed with breast cancer. Five hundred women in the mammography group and 505 in the control group died of the disease.

"[O]ur data show that annual mammography does not result in a reduction in breast cancer specific mortality for women aged 40-59 beyond that of physical examination alone or usual care in the community," the researchers concluded. "The data suggest that the value of mammography screening should be reassessed."

The American College of Radiology and the Society of Breast Imaging responded to the study, calling it "an incredibly misleading analysis based on the deeply flawed and widely discredited Canadian National Breast Screening Study" and argued that its results "should not be used to create breast cancer screening policy as this would place a great many women at increased risk of dying unnecessarily from breast cancer."

To learn more:
- read the article in the British Medical Journal
- check out the article in the New York Times
- see the statement from the ACR and SBI