The U.S. Preventive Services Task Force (USPSTF) has updated its 1996 guidelines for breast cancer screening. The new guidelines recommend screening mammography, with or without a clinical breast examination, every one to two years in all women 40 years and older. The recommendation is supported by at least fair evidence that the benefits outweigh the harms. Evidence supporting regular mammography remains strongest in women 50 to 69 years of age, probably because of the lower incidence of breast cancer among the younger group. The benefit of regular screening also is present in women 70 years and older, probably because of the decreased harms from screening in the older population. Clinical breast examination, either alone or with mammography, has not been determined to have a positive risk-benefit ratio and is not recommended. The value of self-breast examination is not well documented.

Factors that should be considered when discussing mammography risks and benefits with patients include potential harms and benefits and test limitations. Clinicians also should tell women that the balance of benefits and potential harms of mammography improves with increasing age among women aged 40 to 70 years, and that women with an increased breast cancer risk are more likely to benefit from regular mammography. Genetic investigation is not addressed in the USPSTF guidelines. There is little evidence supporting annual mammography over biennial testing in women 40 years of age and older. Screening of older women should take into consideration other comorbid conditions that may limit life expectancy.

Most North American medical organizations support screening, with varying opinions about clinical breast examination. The recommended starting age for mammography is 40 or 50 years, with almost unanimous opinion that high-risk women should begin mammography at 40 years. The question of annual versus biennial screening is also controversial.

In an editorial in the same issue, Sox discusses the validity of the larger studies on the efficacy of mammography, noting the difficulty in comparing results caused by variations in methods of counting cancer deaths. He notes that the appropriate age for beginning breast cancer screening remains undetermined.