Mammography's role in detecting breast cancer reinforced

The Dept. of Health and Human Services supports its use as a screening tool and lowers the recommended age for its initial use.

By Susan J. Landers, amednews staff. March 11, 2002.

Washington -- Stepping into a long-brewing controversy, the federal government endorsed the use of mammography as an effective screening tool for breast cancer.

"The federal government makes a clear recommendation to women on mammography: If you are 40 or older, get screened for breast cancer with mammography every one to two years," said Health and Human Services Secretary Tommy Thompson, at a Feb. 21 news conference.

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The recommendation is based on a review of the scientific literature by the U.S. Preventive Services task force on the effectiveness of mammography at detecting breast cancer and prolonging the lives of women with breast cancer.

While the task force did find that the studies reviewed had limitations, it concluded that there was fair evidence that mammography screening every one to two years could reduce breast cancer mortality by approximately 20% to 25% over 10 years.

The finding not only negates a recent review of the same literature by Danish researchers that questioned the effectiveness of mammography at reducing mortality, but also broadens the recommendations made by the task force in 1996.

An earlier review led the task force to recommend routine breast cancer screening every one to two years for women ages 50 to 69. Since then, new studies and extended follow-up from the earlier trials provided new information on the benefits of breast cancer screening for women 40 and older, according to the task force.

HHS recommends mammograms for women older than 40.

However, the strongest evidence of the benefit of mammography remained among women ages 50 to 69, according to task force documents.

"Mammography is an important tool for detecting breast cancer," said Janet Allan, PhD, RN, vice chair of the task force. "Clinicians and women should discuss individual risk factors to determine when to have the first mammogram and how often to have them after that," she said.

In addition to age, a family history of breast cancer in a mother or sister, having already been diagnosed with breast cancer or having a previous breast biopsy showing atypical hyperplasia would enter into a decision.

The task force acknowledged that there are some risks associated with mammography, namely false-positive readings that could lead to unnecessary biopsies and needless worry.

Same studies, different conclusions

The task force recommendation results largely from its review of the eight randomized controlled trials of mammography (four of mammography alone and four of mammography plus clinical breast examination) that have reported results within 11 to 20 years of follow-up.

The trials are the same ones examined by Danish researchers Ole Olsen and Peter C. Gotzsche, but the conclusions reached are very different. The Danish review, published in the October 2001 issue of The Lancet, found that screening was unjustified because there is no reliable evidence that it reduces mortality from breast cancer.

The benefits of mammograms are strongest for women age 50-69.

That review was criticized by many. "Mammography has received an incredible amount of very aggressive epidemiologic and academic scrutiny. And the studies have received an extraordinary amount of scrutiny," said Robert Smith, PhD, director of cancer screening for the American Cancer Society, soon after The Lancet review was published.

On occasion the "take it for granted" world in science and medicine might lead to erroneous assumptions, he said. But that is not the case with mammography.

The National Cancer Institute also reaffirmed its support for mammography. "Early detection of cancer saves lives and we continue to recommend mammography for women in their 40s and older," said Andrew von Eschembach, MD, NCI director.

The task force also noted that there remains insufficient evidence to recommend for or against routine clinical breast examination alone as a screening tool for breast cancer and insufficient evidence to recommend for or against routinely teaching or performing routine breast self-examination. There were not enough data, said the task force, to determine whether either reduced breast cancer deaths.

The 15-member task force is an independent panel of experts, primarily physicians, representing the fields of family medicine, obstetrics-gynecology, pediatrics, nursing, prevention research and psychology. The panel conducts assessments of scientific evidence for a broad range of preventive services.

ADDITIONAL INFORMATION:

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Breast cancer screening recommendations and materials for clinicians and patients from the U.S. Preventive Services task force (http://www.ahrq.gov/clinic/3rduspstf/breastcancer/)