Cornelia Baines and colleagues have re-estimated overdiagnosis of breast cancer from mammography screening by age group in the Canadian National Breast Screening Study (CNBSS) – a randomized screening trial.
They found ‘substantial overdiagnosis in the CNBSS with estimates that are consistent with other robust published estimates’ and say what is needed is ‘a rigorous definition of the histological criteria of overdiagnosis’ as well as ‘effective methods for communicating the risk of over-diagnosis to policy-makers, the medical profession and the public’.
Their conclusions show high levels of overdiagnosis in both age groups studied (‘approximately 30% of invasive screen-detected breast cancers in women aged 40-49 were overdiagnosed… 20%… aged 50-59’ – ‘Including ductal carcinoma in situ the estimates are 40% and 30% respectively’).
They state, ‘women should be completely informed of the risks of overdiagnosis before they decide to accept breast screening’.
Perhaps all women invited to breast screening should be given a copy of this paper.
Revised estimates of overdiagnosis from the Canadian National Breast Screening Study. Cornelia J Baines, Teresa To, Anthony B Miller. Preventive Medicine. 90 (2016) 66-71.