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Bending the Curve Trial by Trial
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CNBSS

Canadian National Breast Screening Study: randomised screening trial in women aged 40-59

N = 89,835

Population
Women aged 40-59 at 15 screening centres in Canada.
Design
Randomised screening trial at 15 screening centres in six Canadian provinces, 1980-85; women aged 40-59 randomly assigned to five annual mammography screens or control. Women aged 40-49 in the mammography arm and all women aged 50-59 in both arms received annual physical breast examination; women aged 40-49 in the control arm received a single examination followed by usual care in the community. Follow-up to 25 years by linkage to cancer registries and vital statistics.
Primary endpoint
Breast cancer mortality
Arms
  • Mammography (experimental, n = 44,925): Five annual mammography screens (with annual physical breast examination in women aged 40-49 in this arm and in all aged 50-59)
  • Control (control, n = 44,910): No mammography (physical examination for women aged 50-59; single examination then usual care for women aged 40-49)
People
Miller AB
Breast cancer mortalityHR 1.05 (95% CI 0.85–1.30)Breast cancer mortalityHR 0.99 (95% CI 0.88–1.12)
Show the numbers
Results reported for CNBSS
EndpointAnalysisMammographyControlEffect
Breast cancer mortalityWomen with breast cancer diagnosed during the five-year screening period (666 vs 524 invasive cancers)Death from breast cancer diagnosed during the screening period, 25-year follow-uplong term-updateMiller 2014——HR 1.05 (95% CI 0.85–1.30)
Breast cancer mortalityAll randomised women (89,835)Cumulative mortality from breast cancer over the entire study period, 25-year follow-uplong term-updateMiller 2014——HR 0.99 (95% CI 0.88–1.12)
Results reported for CNBSS
EndpointAnalysisMammographyControlEffect
Breast cancer mortalityWomen with breast cancer diagnosed during the five-year screening period (666 vs 524 invasive cancers)Death from breast cancer diagnosed during the screening period, 25-year follow-uplong term-updateMiller 2014——HR 1.05 (95% CI 0.85–1.30)
Breast cancer mortalityAll randomised women (89,835)Cumulative mortality from breast cancer over the entire study period, 25-year follow-uplong term-updateMiller 2014——HR 0.99 (95% CI 0.88–1.12)
Hazard ratio (95% CI) by endpoint. Values below 1 favour the experimental arm.
Breast cancer mortalityBreast cancer mortality0.512◀ experimentalcontrol ▶
Data table
EndpointHR95% CI
Breast cancer mortality1.050.85–1.3
Breast cancer mortality0.990.88–1.12
Primary publication: Miller AB, Wall C, Baines CJ, Sun P, To T, Narod SA. Twenty five year follow-up for breast cancer incidence and mortality of the Canadian National Breast Screening Study: randomised screening trial. BMJ. 2014;348:g366. PubMedDOI

Appears in

Sources

  1. Miller AB, Wall C, Baines CJ, Sun P, To T, Narod SA. Twenty five year follow-up for breast cancer incidence and mortality of the Canadian National Breast Screening Study: randomised screening trial. BMJ. 2014;348:g366.

    PubMedDOI