Canadian National Breast Screening Study
Trial question
What is the role of annual mammography screening in females aged 40-59 years?
Study design
Multi-center
Open label
RCT
Population
89835 female patients.
Inclusion criteria: females aged 40-59 years with no history of breast cancer.
Key exclusion criteria: mammography in the previous 12 months; history of breast cancer; pregnancy.
Interventions
N=44925 mammography (annual physical breast examinations).
N=44910 no mammography (a single examination followed by usual care in the community).
Primary outcome
Deaths from breast cancer in follow-up period
1.11%
1.12%
1.1 %
0.8 %
0.6 %
0.3 %
0.0 %
Mammography
No
mammography
No significant
difference ↔
No significant difference in deaths from breast cancer in the follow-up period (1.11% vs. 1.12%; HR 0.99, 99% CI 0.88 to 1.12).
Secondary outcomes
No significant difference in all-cause mortality in the follow-up period (10.66% vs. 10.44%; HR 1.02, 95% CI 0.98 to 1.06).
Conclusion
In females aged 40-59 years with no history of breast cancer, mammography was not superior to no mammography with respect to deaths from breast cancer in the follow-up period.
Reference
Anthony B Miller, Claus Wall, Cornelia J Baines et al. Twenty five year follow-up for breast cancer incidence and mortality of the Canadian National Breast Screening Study: randomised screening trial. BMJ. 2014 Feb 11;348:g366.
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