NEWS

Mammography Guidelines in the National Spotlight . . . Again

Katherine Arnold

In what the government has said is its final word on mammography, a new review of evidence from the U.S. Preventive Services Task Force recommends that all women older than age 40 have a mammogram every 1 to 2 years.

The announcement came on the heels of intense media coverage of breast cancer screening. Inspired in part by the somewhat controversial conclusions of last October’s Cochrane review of mammography, the renewed spotlight put many advocacy groups and cancer organizations on the defensive. The National Cancer Institute sent out a statement at the end of January reinforcing its breast cancer screening recommendations, and groups such as the Komen Foundation and the National Alliance of Breast Cancer Organizations blanketed their Web sites with criticisms of the review.

USPSTF completed its 2-year evaluation process this January and plans on publishing the entire scientific review later this year. Last month the task force released an abbreviated form of its recommendations, which was prompted by the renewed interest in the topic, said Alfred Berg, M.D., chair of USPSTF and professor and chair of the Department of Family Medicine at the University of Washington, Seattle.

This latest guidance on screening mammography expands the task force’s 1996 recommendations, which found "good" evidence to recommend screening mammograms for women ages 50 to 69. At that time, the task force found that the evidence was inconclusive to recommend regular mammograms for women ages 40 to 49 and for women older than age 70.

The new evidence report recommends that all women over age 40 have regular mammograms, but the task force deemed the evidence "fair"—which ranks lower on the task force’s rating scale. However, Berg pointed out that the methodology for the new report was different and cannot be directly compared to the previous report.

"We did not find a bright line dividing the evidence at age 50," Berg said. "Our new review points out that the balance of benefits to harms changes on a continuum, becoming more favorable with age."

The report acknowledges that the evidence is strongest for women aged 50–69. "For women aged 40–49, the evidence that screening mammography reduces mortality from breast cancer is weaker, and the absolute benefit of mammography is smaller, than it is for older women," the report noted.

Conflicting Reports?

On the surface, USPSTF’s recommendations seemed to be at odds with a review released last October, authored by Ole Olsen and Peter C. Gotzsche, M.D., of the Nordic Cochrane Centre, which concluded that screening mammography offers no overall mortality benefit.

Both the task force and the Cochrane group analyzed all available data on screening mammography—the results of eight randomized clinical trials that have enrolled patients and reported results over the last three and a half decades. Both groups acknowledge that nearly every trial had flaws, but varying interpretations of the severity of those flaws led the two groups to opposite conclusions.

One major difference in the analyses was the interpretation of the appropriate end point. The Cochrane group maintained that, if mammography is an effective screening tool, its benefits should be measurable in terms of overall mortality. Disease-specific mortality, or deaths specifically from breast cancer, is a biased end point, they said. On this premise, the Cochrane group excluded some of the trials from its final analysis that led them to its broadly publicized conclusion. (See News, Nov. 21, 2001, p. 1678.)

However, Janet Allan, Ph.D., co-chair of USPSTF and dean of the University of Texas Health Sciences Center in San Antonio, said that the task force acknowledged that, while many of the trials were flawed, it does not mean that they should be omitted from analysis.

"The outcome measure that [the studies] were designed to look at was death from breast cancer," Allan said. "They were not designed to look at outcome measures from all-cause mortality. It’s an unfair criticism on the part of the Nordic Center to say that the studies are flawed because they did not look at all-cause mortality. They were not designed to do that."

‘Polarization of Views’

The two analyses highlight a polarization of views, said Barron Lerner, M.D., Ph.D., associate professor of medicine and public health at Columbia University, New York. "Different people on different sides of the issue interpret data differently and come to opposite conclusions," he said. "There’s almost nobody left in the middle asking why it is that such respected statisticians on both sides of the issue are coming up with different conclusions."

But, statistical issues aside, the task force’s recommendations have left some experts concerned about the message women are getting.

"The uncertainties haven’t been fully explained," said Maryann Napoli, associate director of the Center for Medical Consumers in New York.

She noted that the task force’s report gave short shrift to the concept of overdiagnosis and that it did not give an adequate explanation of ductal carcinoma in situ and the possibility of overtreatment of this disease.

"Instead of telling women what to do, the government should be explaining the strengths and weaknesses of the supporting evidence—the harms, including the overtreatment of DCIS, as well as the benefits—and then let women decide," said Napoli. "[Mammography] is not a risk-free activity."

But mammography has always been a political hot button topic, and this latest announcement prompted Congress to call a hearing to explore the issues. At a joint hearing of the Senate Subcommittee on Public Health and the Committee on Appropriations, Fran Visco, president of the National Breast Cancer Coalition, called for a more open acknowledgment of the flaws of mammography.

"Our goal should not be to provide a clear, simple message," Visco said. "Our goal should be, ‘let’s find the truth about what will save women’s lives, and let’s get that information and those interventions to women.’ A clear, simple message, while comforting, is not necessarily correct."

So, while mammography finds itself once again in the political and media spotlight, what is the take-home message for women over age 40? Health and Human Services Secretary Tommy Thompson made his opinion clear: "The task force recommendation sends a very powerful and clear message about the value of mammography as an early detection tool that can help save lives," he said.

But others suggest that the answer is not that simple. "[The current debate] makes the situation appear like it’s an either-or, but it’s not. These are hard points to try to make," Lerner said. "If the data indeed show mixed signals, then women deserve to know that there are mixed signals."


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