Archie Bleyer1,†,*, Cornelia Baines 2 and Anthony B. Miller 2
Version of Record online: 15 DEC 2015 DOI: 10.1002/ijc.29925
© 2015 UICC
Issue International Journal of Cancer
International Journal of Cancer
Volume 138, Issue 8, pages 2003–2012, 15 April 2016
Archie Bleyer, MD is Chair of the Institutional Review Board for the St. Charles Health System in Central Oregon and author/co-author of over 100_original_reports on clinical research that required CISR approval. He is also a clinical research professor.
Archie Bleyer, Professor of Clinical Research at the Oregon University of Science and Health published together with G.Welch, American cancer researcher in 2012 in the NEJM, an update on the effects of three decades of screening on breast cancer incidence from 1978 to 2008. The finding of the study was that the small reduction observed in advanced cancers was not proportional to the impressive increase (doubling) in the early stage cancers.
This year Archie Bleyer and Tony Miller, Professor Emeritus at the University of Toronto, who conducted a 25-year follow-up study of women from Canadian trials*, are studying the extent to which reduced breast cancer mortality is attributable to screening mammography. The authors examine the impact of screening mammography along three dimensions:
1) A chronology study, to see if the decline in breast cancer mortality would be correlated with the introduction of screening campaigns.
2) A magnitude study to examine whether the decline in mortality would be proportional to the rate of screening mammography.
3) And then, an analogy study, by studying the mortality reduction model for other forms of cancer, for which population screening is not conducted.
Regarding the first two axes of study, using data from eight European and North American countries, the authors find no correlation between the penetration of national screening and either the chronology or magnitude of national breast cancer mortality reduction.
(Indeed, since the 1990s, cancer mortality has been decreasing, but the reasons highlighted by other studies (Autier, Jorgensen, Kalager) are essentially therapeutic progress, and perhaps the effects of real prevention campaigns against risk factors are also being seen)
The magnitude of the mortality decline is even greater in the unscreened, younger women than in the screened population, as observed in the United States.
There is no correlation between the extent of screening and the magnitude of the decrease in cancer mortality in recent years.
Finally, the comparative study of 14 other types of cancers shows a similar decline in mortality rates for these cancers, even though these other cancers are not subject to screening campaigns.
*Twenty five year follow-up for breast cancer incidence and mortality of the Canadian National Breast Screening Study: randomised screening trial.
BMJ 2014; 348 doi: http://dx.doi.org/10.1136/bmj.g366 (Published 11 February 2014)
Quote this as: BMJ 2014;348:g366 https://www.bmj.com/content/348/bmj.g366
The authors conclude that the degree to which observed reductions in breast cancer mortality is attributable to screening mammography has become increasingly controversial.
A comparison of eight countries in Europe and North America shows no correlation between national screening penetration and either the chronology or magnitude of national breast cancer mortality reduction.
Evidence from the three different approaches and other additional observations do not support the hypothesis that mammography screening is a primary reason for breast cancer mortality reduction in Europe and North America.
See also: https://www.bmj.com/content/343/bmj.d4411
Pr P. Autier conclusions: The contrast between the timing of breast cancer screening being implemented and the similarity in mortality reduction between the country pairs do not suggest that a large proportion of the mortality reduction can be attributed to mammography screening.