shown to be of minor significance. The remaining minor considerations did not detract from the conclusion that screening mammography reduced the mortality from breast cancer in women receiving an invitation to be screened in well-organized clinical trials: The reduction in breast cancer mortality appeared to be between 21 and 23 percent, according to recent estimates. Those participating fully could expect greater benefit.

There was unanimity that with the current evidence from randomized trials, taking full account of any limitations to their methodology, there were no grounds for stopping on-going screening programs or planned programs.

The group also stated that mammographic screening is only one step in the total management of the woman with breast cancer. This goal can only be attained through rigorous, high-quality screening, diagnosis, and treatment.

United States Preventive Services Task Force (USPSTF) September 2002

The USPSTF is an independent panel of experts in primary care and prevention that systematically reviews the evidence of effectiveness of clinical preventive services and develops recommendations for their use.

The USPSTF concluded that the criticisms made against the Swedish trials by Gotzsche and Olsen are misleading and scientifically unfounded. “We found the same flaws [as Gotzsche and Olsen],” says Janet D. Allan, vice-chair of the task force and dean of the School of Nursing at the University of Texas Health Science Center in San Antonio. “They interpreted the flaws as being fatal flaws,” she says. “We did not interpret the flaws as fatal…and concluded that the studies were still valid and that mammography screening reduces deaths from breast cancer.”

The USPSTF concluded that the absolute benefit among women in their 40s is smaller than it is among older women because the incidence of breast cancer is lower at the younger age. The USPSTF also concluded that the evidence is also generalizable to women aged 70 and older (who face a higher absolute risk for breast cancer) if their life expectancy is not compromised by comorbid disease. The absolute probability of benefits of regular mammography increase along a continuum with age, whereas the likelihood of harms from screening (false-positive results and unnecessary anxiety, biopsies, and cost) diminish from ages 40 to 70. The balance of benefits and potential harms, therefore, grows more favorable as women age. The precise age at which the potential benefits of mammography justify the possible harms is a subjective choice.

the availability of screening reduces mortality from breast cancer by 20 to 30 percent (reviewed by Duffy and colleagues in 2003),19 and that in a population that actually participates in screening mammography, the reduction can be considerably greater, nearly 50 percent.18,97 This is not to say that every woman who undergoes screening mammography will ben-



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