No abstract

REAST CANCER SCREENING, ESpecially with mammography, has been recommended for many decades, 1 and the majority of women older than 40 years in the United States participate in screening activities. 2,3 Meanwhile, new screening modalities have been introduced, and some of these have been increasingly incorporated into community practice. However, none of the new technologies has been evaluated for its effect on breast cancer mortality. Community practice of screening may differ from the care provided within randomized clinical trials and is less often discussed in review articles. Reviews of breast cancer screening usually emphasize efficacy and results of randomized trials, particularly those involving screen-film mammography. 4-7 Efficacy of a screening tool is measured in experimental studies under ideal circumstances. 8 In contrast, effectiveness is defined as the extent to which a specific intervention "when deployed in the field in routine circumstances, does what it is intended to do for a specific population." 8 We systematically reviewed what is known about the community practice of mammography, clinical breast examination, and breast self-examination, when possible, comparing the results from community studies with CME available online at www.jama.com

Randomized trials have provided stronger scientific evidence regarding the effectiveness of screening for breast cancer than for any other cancer. However, much still needs to be learned. Periodic gatherings of scientists in the field should speed the process.

A 44-year-old woman who is a new patient has no known current health problems and no family history of breast or ovarian cancer. Eighteen months ago, she had a normal screening mammogram. She recently read that mammograms may not help to prevent death from breast cancer and that "the patient should decide." But she does not think she knows enough. She worries that there is a breast-cancer epidemic. What should her physician advise? THE CLINICAL PROBLEM In 1990, for the first time in 25 years, mortality from breast cancer in the United States began dropping; by 1999, the age-adjusted mortality rate was at its lowest level (27.0 per 100,000 population) since 1973. 1 Meanwhile, by 1997, 71 percent of women in the United States who were 40 years of age or older reported having undergone mammography during the previous two years-an increase from 54 percent in 1989. 2 Ironically, just as screening (or better treatment or both) seemed to be lowering mortality from breast cancer nationally, questions were raised about the validity of the studies that had led to widespread screening. For more than two decades, expert groups uniformly agreed that screening mammography reduces mortality from breast cancer among women in their 50s and 60s, even though they disagreed about other age groups. 3 However, questions were raised in 2000, when two Danish investigators concluded that only three of eight randomized trials were of sufficient quality to determine the effectiveness of mammography and that the combined results of these three trials showed no benefit. This report led to confusion about the usefulness of screening mammography. STRATEGIES, EVIDENCE, AND AREAS OF UNCERTAINTY Women are interested in knowing about breast cancer and want information from their doctors. 4,5 When women and their physicians are making decisions about screening, they need information about the underlying risk of the condition being screened for, the effectiveness of the procedure in preventing an untoward outcome such as death, and the potential ill effects of screening, such as false positive tests. (For policymakers and payers, cost effectiveness is an important factor in decisions about the allocation of finite resources.) Clinical information about each of these issues with regard to breast cancer and mammography is summarized below.