Two Studies Challenge Mammography Guideline Changes

November 28, 2012

CHICAGO - USPSTF’s mammography screening guidelines to a decline in screening and may lead to a significant number of missed cancers, researchers found.

CHICAGO - There are few more intensely personal, and complicated, decisions than that of undergoing a mammography. In two new studies presented Tuesday at RSNA, researchers sought to quantify the impact of revised screening guidelines issued by the U.S. Preventive Services Task Force in 2009.

Researchers found that the guidelines led to a decline in screening mammograms and may lead to a significant number of missed cancers. The USPSTF recommendations moved the age of routine screening from 40 to 50, discouraged screenings after age 74 and recommended screening every two years instead of annually.

"Recommendations on screening mammography are extremely important public policy and we wanted to contribute to that dialogue," said Elizabeth Arleo, MD, assistant professor of radiology at New York Presbyterian Hospital, Weill Cornell Medical College in New York City. "We get questions all day long from patients and referring physicians on the appropriateness of screening mammography. The inconsistent information is very confusing for everyone."

Historically, the USPSTF, the American Cancer Society and the American College of Radiology have all encouraged yearly routine mammography in women 40 years of age and older. The new studies aimed to analyze the impact of the new recommendations on women ages 40 to 49 and female Medicare beneficiaries in 2010, the first full year after the new recommendations were released.

The latter study analyzed data from the Medicare Part B Physician/Supplier Procedure Summary Master Files for 2005 to 2010. Researchers calculated the annual rate of screening mammograms per 1,000 female Medicare beneficiaries. In those years, there was a 0.9 percent increase in the compound annual growth rate of mammograms, consistent with the yearly growth rate since 2001. But the change from 2009 to 2010, the year after the recommendations, was instead a 4.3 percent decrease.

It's not initially clear what caused for the abrupt drop in 2010. “It could have been that women who followed the task force recommendations over the age of 74 just stopped getting screened... Or it could also be perhaps that women extended, or decided to extend their screening interval from one to two years,” said co-author David C. Levin, MD of the department of radiology at Thomas Jefferson University Hospital in Philadelphia.

“What is clear is that the introduction of those task force recommendations in late 2009 had a chilling effect on the willingness of women to get screened. It remains to be seen whether this trend is going to continue in 2011 and beyond and whether it will affect breast cancer mortality,” he said.

To predict how the recommendations might affect women in their 40s, Arleo's retrospective study analyzed screening mammography data from 2007 to 2010.

Over the four year period, 43,351 screening mammograms were performed, of which 1,227 biopsies were recommended, which led to the detection of 205 breast cancers. 33 percent of the total mammograms were performed on women in their 40s. From these, 413 biopsies were recommended, which led to the detection of 39 breast cancers. Only 8 percent of these women had immediate relatives with premenopausal breast cancer.

"Nearly 20 percent of cancers detected with screening mammography were found among women in their 40s,” Arleo said. "It seems unacceptable to potentially miss nearly 20 percent of the breast cancers we are identifying. This, in our view, would represent a substantial degree of under-diagnosis."