Independent researchers from the U.S. and Norway have revealed data showing that screening mammography programs reduce deaths from breast cancer and incidences of late-stage breast cancers.

Digital MammographyTwo recent studies shed new light on the importance of screening mammography, which has been the subject of debate since a 2009 revision to U.S. Preventive Services Task Force (USPSTF) recommendations for breast cancer screening with mammography. Despite calls for limited access to or discontinuation of screening mammography, researchers in the U.S. and Norway have independently concluded that mammography saves lives.

Background to the Screening Mammography Controversy

In 2009, the USPSTF reversed a 2002 decision to recommend annual screening mammography beginning at age 40. The new guidelines recommended against screening mammography for women aged 40 to 49 and recommended screening mammography every two years for women aged 50 to 74.

While accepted by some, the revised USPSTF guidelines contradict screening recommendations issued by organizations including the American Cancer Society, Society of Breast Imaging and American College of Radiology. Additionally, these new guidelines were issued along with a USPSTF report, published November 2009 in the Annals of Internal Medicine, which determined that screening mammography reduced breast cancer mortality among women aged 39 to 49 by 15 percent.

Since the USPSTF revised its screening mammography guidelines, several researchers and members of the medical community have called for recommendations to be cut further. For instance, authors of the 25-year follow-up to the Canadian National Breast Screening Study (CNBSS), published February 2014 in BMJ,determined that screening mammography was ineffective and “should be urgently reassessed by policy makers.”

These results, and others condemning screening mammography, have been rightfully criticized and should not be used to influence policy. In the case of CNBSS results:

  • Mammography technology used in the study was from the 1970s, outdated even when the study began, and does not reflect capabilities of modern mammography machines and techniques.
  • Mammographic images examined did not employ standard views implemented in 1985.
  • Radiologic technicians performing exams studied were not trained specifically in mammography.
  • Radiologists reading exams studied were not trained specifically in breast imaging.
  • Women studied were possibly not appropriately assigned to mammography and control groups, which means this was not truly a randomized controlled study.

Many clinicians, medical researchers, patient advocates and public health professionals have made convincing arguments to debunk these claims. The American College of Radiology and Society of Breast Imaging issued a statement that declared:

“Coupling the fundamentally corrupted allocation process with the documented poor quality of the mammography screening should have long ago disqualified the CNBSS as a legitimate trial of modern screening mammography.”

Mammography Leads to Fewer Late Stage Breast Cancers, Reduction in Breast Cancer Mortality

For decades, evidence supporting the life-saving potential of screening mammography has accumulated. Separate studies published June 2014 in peer-reviewed journals Cancerand BMJ provide some of the most recent evidence available pointing to the benefits of screening mammography.

In one, researchers from the University of Michigan Comprehensive Cancer Center in Ann Arbor analyzed breast cancer diagnosis data collected from 1977 to 1979 and compared it with data collected from 2007 to 2009. Early-stage breast cancer incidence increased by nearly one-half, which suggests a greater overall breast cancer incidence today than 30 years ago, but late-stage breast cancers decreased by 37 percent from projected rates from the 1970s.

These results indicate a shift toward earlier detection of breast cancers, which is the express purpose of screening mammography, according to lead study author Mark Helvie, M.D.:

“This is what you would expect from a successful screening program. Not only are we detecting more early-stage cancer, but we are decreasing the number of late-stage cases that tend to be more challenging to treat and more deadly.”

In a study of Norwegian women, led by Harald Weedon-Fekjaer, Ph.D., of the Norwegian University of Science and Technology and the University of Oslo, researchers examined data collected from 1986 to 2009 on women aged 50 to 79 and found that invitation to a screening mammography program resulted in a 28 percent reduction in risk of death from breast cancer.

Results of the Norwegian study were quickly criticized for showing benefits that were “modest at best,” as two professors of medicine from the University of Washington and the University of North Carolina wrote in a June 2014 editorial in BMJ. They reference harms, such as the potential for false positive results and psychological stress, as well as the fact that only one life is saved per 368 women invited into the screening mammography program.

While being brought back for additional testing after a false positive mammography result can certainly cause anxiety, and physicians should certainly consider anxiety while caring for patients, is it really fair to tell the women saved by screening mammography that its results are “modest at best”?

Screening Mammography in the Future

The USPSTF is currently reviewing its 2009 decision to recommend against screening mammography. Because health insurers take into account USPSTF breast cancer screening when deciding what services should and should not be covered, there is potential for these guidelines to have significant effect on women across the country.

Mammography may not be perfect – it may fail to detect some breast cancers and it may produce some false positive results. However, numerous randomized controlled trials have proven, and the USPSTF agrees, that routine screening mammography beginning at age 40 saves lives.

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