The Canadian National Breast Screening Study-1: breast cancer mortality after 11 to 16 years of follow-up. A randomized screening trial of mammography in women age 40 to 49 years
- 1University of Toronto, Toronto, Canada. a.miller@dkfz-heidelberg.de
- 0University of Toronto, Toronto, Canada. a.miller@dkfz-heidelberg.de
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View abstract on PubMed
Summary
This summary is machine-generated.Annual mammography screening for women aged 40-49 did not reduce breast cancer mortality. This large trial found no significant difference in deaths between screening and usual care groups.
Area Of Science
- Oncology
- Preventive Medicine
- Radiology
Background
- The effectiveness of breast cancer screening in women aged 40-49 is debated.
- This age group presents unique challenges for screening efficacy.
Purpose Of The Study
- To compare breast cancer mortality rates in women aged 40-49 undergoing regular screening versus those receiving standard community care.
- To evaluate the long-term impact of mammography, clinical breast exams, and breast self-examination instruction.
Main Methods
- Individually randomized controlled trial involving 50,430 women aged 40-49.
- Intervention group received annual mammography, breast physical examination, and breast self-examination instruction for 4-5 years.
- Control group received usual community care after an initial examination and instruction.
Main Results
- No significant reduction in breast cancer mortality was observed in the screening group compared to the usual care group (rate ratio 1.06).
- The screening group had a higher incidence of invasive and in situ breast cancer diagnoses.
- Mammography successfully detected nonpalpable and small invasive tumors.
Conclusions
- Four to five annual screenings did not decrease breast cancer mortality in women aged 40-49 over 11-16 years.
- The study suggests that significant mortality reduction (≥20%) from this screening regimen in this age group is unlikely.
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