By Brendon Nafziger and Heather Mayer, DOTmed News reporters

A study on mammography screening in Norway finds the health benefits more modest than expected, drawing the ire of radiologist groups and re-igniting a debate on screening that started last November.

In a study analyzing tens of thousands of breast cancer cases published Thursday in the New England Journal of Medicine, researchers said the availability of screening mammography only accounted for one-third of the decline in breast cancer deaths.
"[T]he difference in the reduction in mortality...that could be attributed to screening alone was 2.4 deaths per 100,000 person-years, or a third of the total reduction of 7.2 deaths" per 100,000 person-years seen over the past few decades, wrote the researchers, led by Dr. Mette Kalager of Oslo University Hospital.

The researchers compared breast cancer death rates for women living in counties invited to screening and those not invited, with similar groups in the past. For women aged 50 to 69 invited to receive mammograms once every two years, the death rate fell by 10 percent. But for women over 70, who were not encouraged to get the breast exams, the death rate fell by 8 percent.

The authors said they had expected a 30 percent cut in the death rate, according to Reuters.

In an accompanying editorial, Dr. Gilbert Welch of Dartmouth Medical School said the results suggest that for every 2,500 women getting a mammogram, only one would be saved from breast cancer, and that more than 500 would get a biopsy, according to Reuters. Of these, five to 15 would be treated for something that would never actually harm them.

The study tosses kindling onto a debate that has been burning since last year, when the U.S. Preventive Services Task Force recommended women receive mammograms once every two years instead of annually. The group also suggested women begin getting screened at age 50, not 40, as previously recommended.

These suggestions, which would have brought American screening practice in line with much of Europe's, drew widespread criticism from some medical groups, women's lobbies and equipment manufacturers, who criticized the panel for basing its conclusions on speculative computer models and for not having the correct specialists on the panel.

"The total body of the science supports the fact that regular mammography is an important part of a woman's preventive health care," said chief medical officer of the American Cancer Society, Dr. Otis Brawley, in prepared remarks sent to DOTmed News. "Following the American Cancer Society's guidelines for the early detection of breast cancer improves the chances that breast cancer can be diagnosed at an early stage and treated successfully."

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