Screening mammography: a successful public health initiative

Abstract

This paper reviews the ability of screening mammography to reduce breast cancer death rates, and it discusses methods that maximize benefits and reduce false-positive interpretations in a screening program. The review covers published results from screening mammography programs conducted in Europe and North America, along with quality assurance measures designed to ensure that similar or even better outcomes will be shared by other populations of screened women. Randomized trials in Europe and the United States of America have shown the benefit from screening women ages 40-70 years. Encouraged by the success of these trials, many Scandinavian countries now offer screening mammography to their populations as a public health service. These service screening programs have reduced breast cancer deaths as much as 63% among women who were screened. In the United States, where 61.5% of women age 40 and older report having had a mammogram in the preceding year, death rates from breast cancer have been falling despite an increasing incidence of the disease. The technical quality of mammography in the United States has improved as a result of advances in mammography equipment, including the film-screen systems. Also contributing to the improvement has been the implementation of federally mandated quality control testing at each mammography facility, as required by the Mammography Quality Standards Act (MQSA), which the Congress of the United States approved in 1992. Factors that result in increased detection of early-stage cancers include better technique, use of two mammographic views per breast, annual screening intervals, and improved interpretation. Mammography is one of the 10 major subject categories on the American Board of Radiology examinations. Furthermore, MQSA requires radiologists who practice mammography to obtain continuing medical education credits and to use standard interpretation assessments on every report. Manuals for technical quality control and breast imaging reporting, as well as education and self-assessment materials on interpretation, have been developed by the American College of Radiology. Even though mammography will not detect all breast cancers, it is still the best available screening test. The American Cancer Society recommends that annual screening mammography begin no later than age 40 years.