Impact of screening mammography on breast cancer mortality

• Published in: International journal of cancer 2016-04, Vol.138 (8), p.2003-2012
• Main Authors: Bleyer, Archie, Baines, Cornelia, Miller, Anthony B.
• Format: Article
• Language: English
• Subjects: Adult; Age Distribution; Breast cancer; Breast Neoplasms - diagnostic imaging; Breast Neoplasms - mortality; Cancer; Early Detection of Cancer - mortality; Female; Humans; Mammography; Mammography - mortality; Medical research; Medical screening; Middle Aged; Mortality; mortality benefit; screening mammography; SEER Program
• ISSN: 0020-7136; 1097-0215
• DOI: 10.1002/ijc.29925

The degree to which observed reductions in breast cancer mortality is attributable to screening mammography has become increasingly controversial. We examined this issue with three fundamentally different approaches: (i) Chronology—the temporal relationship of the onset of breast cancer mortality decline and the national implementation of screening mammography; (ii) Magnitude—the degree to which breast cancer mortality declined relative to the amount (penetration) of screening mammography; (iii) Analogy—the pattern of mortality rate reductions of other cancers for which population screening is not conducted. Chronology and magnitude were assessed with data from Europe and North America, with three methods applied to magnitude. A comparison of eight countries in Europe and North America does not demonstrate a correlation between the penetration of national screening and either the chronology or magnitude of national breast cancer mortality reduction. In the United States, the magnitude of the mortality decline is greater in the unscreened, younger women than in the screened population and regional variation in the rate of breast cancer mortality reduction is not correlated with screening penetrance, either as self‐reported or by the magnitude of screening‐induced increase in early‐stage disease. Analogy analysis of United States data identifies 14 other cancers with a similar distinct onset of mortality reduction for which screening is not performed. These five lines of evidence from three different approaches and additional observations discussed do not support the hypothesis that mammography screening is a primary reason for the breast cancer mortality reduction in Europe and North America. What's new? Deaths from breast cancer have declined steeply since the 1990s, though although the reasons for this progress remain unclear. The role of screening mammography, presumably the most effective breast cancer screening modality, has been notably enigmatic and controversial. Its effectiveness is further drawn into question here, in which scrutiny of data from eight countries in Europe and North America indicates that screening mammography has little impact on breast cancer mortality reduction. Screening mammography correlated with neither the onset nor magnitude of mortality declines. Indeed, advances in treatment likely have had a greater relative impact on breast cancer survival.