title: The evidence base for breast cancer screening.
abstract: The history of breast cancer screening is littered with controversy. With 10 trials spanning 4 decades, we have a substantial body of evidence, but with different aims and flaws. Combined analysis of the intention-to-treat results gives an overall relative reduction in breast cancer mortality of 19% (95% CI 12%-26%), which, if adjusted for non-attendance gives an approximate 25% relative reduction for those who attend screening. However, given that 4% of all-cause mortality is due to breast cancer deaths, this translates into a less than 1% reduction in all-cause mortality. An emerging issue in interpretation is the improvements in treatment since these trials recruited women. Modern systemic therapy would have improved survival (models suggest between 12% and 21%) in both screened and non-screened groups, which would result in a lesser difference in absolute risk reduction from screening but probably a similar, or slightly smaller, relative risk reduction. However benefits and harms, particularly over-diagnosis, need to balanced and differ by age-groups. The informed views of recipients of screening are needed to guide current and future policy on screening.
authors.affiliation: Centre for Research in Evidence-Based Practice, Bond University, Gold Coast, 4229 Australia. pglaszio@bond.edu.au
authors.forename: Paul
authors.initials: P
authors.lastname: Glasziou
authors.forename: Nehmat
authors.initials: N
authors.lastname: Houssami
mesh_terms: D001943:Breast Neoplasms / Q000175:diagnosis* / Q000453:epidemiology / Q000517:prevention & control; D055088:Early Detection of Cancer / Q000379:methods*; D019317:Evidence-Based Medicine / Q000379:methods*; D005260:Female; D007722:Health Knowledge, Attitudes, Practice; D006801:Humans; D011315:Preventive Medicine; D040242:Risk Reduction Behavior; D016387:Women's Health