Studies Add Fuel to Mammography Debate

Two studies presented at the annual meeting of the Radiological Society of North America November 25–30 in Chicago suggest that recommendations for breast cancer screening issued in 2009 by the U.S. Preventive Services Task Force (USPSTF) may lead to missed cancers and a decline in screening.

The studies analyzed the impact of the USPSTF guidelines, which represent a dramatic departure from American Cancer Society guidelines that, for years, have recommended routine screening for all women over the age of 40. The USPSTF guidelines no longer recommend routine screening for women under the age of 50, increase intervals between mammograms from 1 to 2 years, and stop routine screening for women over the age of 74.

The first study was a retrospective review of 43,351 screening mammograms performed from 2007 to 2010 at New York–Presbyterian Hospital/Weill Cornell Medical College, in which 205 cancers were detected.

“The main finding is that patients in their 40s accounted for 19% of screen-detected breast cancers in this study and over half of the cancers in this group were invasive,” notes author Elizabeth Arleo, MD, assistant professor of radiology at Weill Cornell Medical College in New York, NY. “In addition, only 8% of these women had a family history of breast cancer in a first-degree relative. Thus, 92% of women with breast cancer in their 40s did not have an elevated risk and would not have been screened based on the USPSTF 2009 guidelines.”

A second study, led by David Levin, MD, professor and chairman emeritus of the department of radiology at Thomas Jefferson University Hospital in Philadelphia, PA, looked at Medicare data from 2005 to 2010 and found that, among 1,000 female Medicare beneficiaries, the screening mammography rate decreased from 323 in 2009 to 309 in 2010. “While these numbers were low to begin with, from 2005 to 2009 there was a gradual, progressive increase in screening of about 1% per year,” says Levin. “However, in 2010, there was an abrupt 4.3% decrease. We're concerned about the trend.”

The USPSTF recommends that, prior to age 50, the decision to take part in regular, biennial screening mammography “should be an individual one and take patient context into account, including the patient's values regarding specific benefits and harms.” The USPSTF contends that early screening increases the risk of overdiagnosis and overtreatment of cancers that would not have become invasive.

This argument received some supporting evidence from a recent study reported in the New England Journal of Medicine, which estimated that more than 70,000 breast cancers were overdiagnosed in 2008.

“More research is required to determine which cancers are destined to progress and which may be more indolent,” adds Arleo, who supports the American College of Radiology and American Cancer Society recommendations to begin annual screening at age 40.