Time lag to benefit after screening for breast and colorectal cancer: meta-analysis of survival data from the United States, Sweden, United Kingdom, and DenmarkBMJ 2013; 346 doi: https://doi.org/10.1136/bmj.e8441 (Published 08 January 2013) Cite this as: BMJ 2013;346:e8441
- Sei J Lee, assistant professor of medicine1,
- W John Boscardin, associate professor of medicine and biostatistics2,
- Irena Stijacic-Cenzer, senior biostatistician1,
- Jessamyn Conell-Price, University of California medical student3,
- Sarah O’Brien, evaluation analyst4,
- Louise C Walter, professor of medicine1
- 1Division of Geriatrics, University of California (San Francisco), San Francisco Veterans Affairs Medical Center, San Francisco, CA 94121, USA
- 2Department of Epidemiology and Biostatistics, University of California (San Francisco), USA
- 3Joint Medical Program, University of California (San Francisco and Berkeley), San Francisco, USA
- 4AIDS Education and Training Evaluation Center, University of California (San Francisco), USA
- Correspondence to: S J Lee
- Accepted 4 December 2012
Objectives To determine a pooled, quantitative estimate of the length of time needed after breast or colorectal cancer screening before a survival benefit is observed.
Design Meta-analysis of survival data from population based, randomized controlled trials comparing populations screened and not screened for breast or colorectal cancer. Trials were identified as high quality by reviews from the Cochrane Collaboration and United States Preventive Services Task Force.
Setting Trials undertaken in the United States, Denmark, United Kingdom, and Sweden.
Population Screened patients older than 40 years.
Primary outcome measures Time to death from breast or colorectal cancer in screened and control populations.
Interventions Fecal occult blood testing for colorectal cancer screening, mammography for breast cancer screening.
Results Our study included five and four eligible trials of breast and colorectal cancer screening, respectively. For breast cancer screening, 3.0 years (95% confidence interval 1.1 to 6.3) passed before one death from breast cancer was prevented for every 5000 women screened. On average across included studies, it took 10.7 years (4.4 to 21.6) before one death from breast cancer was prevented for 1000 women screened. For colorectal cancer screening, 4.8 years (2.0 to 9.7) passed before one death from colorectal cancer was prevented for 5000 patients screened. On average across included studies, it took 10.3 years (6.0 to 16.4) before one death from colorectal cancer was prevented for 1000 patients screened.
Conclusions Our results suggest that screening for breast and colorectal cancer is most appropriate for patients with a life expectancy greater than 10 years. Incorporating time lag estimates into screening guidelines would encourage a more explicit consideration of the risks and benefits of screening for breast and colorectal cancer.
We thank Laszlo Tabar, who provided data from the Two-County: Ostergotland Mammography study; and Sue Moss and J H Scholefield, who provided data from the Nottingham Faecal Occult Blood Test study.
Contributors: SJL conceptualized the study and drafted the manuscript. WJB led the statistical analysis and made critical revisions to the manuscript. IS-C did the statistical analysis and made critical revisions to the manuscript. JC-P conducted the literature review and extracted data from publications. SO’B extracted data from publications and made critical revisions to the manuscript. LCW provided oversight over all aspects of this project. SJL is the study guarantor. All authors had full access to all of the data in the study and take responsibility for the integrity of the data and the accuracy of the data analysis.
Funding: This work was supported by the Veterans Affairs Medical Center, San Francisco, CA. The funders had no role in the design and conduct of the study; collection, management, analysis, and interpretation of the data; preparation, review, or approval of the manuscript; and the decision to submit the manuscript for publication.
Competing interests: All authors have completed the ICMJE uniform disclosure form at www.icmje.org/coi_disclosure.pdf (available on request from the corresponding author) and declare: support from the San Francisco Veterans Affairs Medical Center and Division of Geriatrics, University of California, San Francisco for the submitted work; SJL was supported by Hartford Geriatrics Health Outcomes Research Scholars Award, the Hellman Family Award for Early Career Faculty at University of California (San Francisco), K23AG040779 from the American Federation of Aging Research and National Institute on Aging, and KL2RR024130 from the National Center for Research Resources, a component of the National Institutes of Health; LCW was supported by R01CA134425 from the National Cancer Institute and K24AG041180 from the National Institute on Aging administered by the Northern California Institute for Research and Education; no financial relationships with any organizations that might have an interest in the submitted work in the previous three years; no other relationships or activities that could appear to have influenced the submitted work.
Ethics approval: The Committee on Human Research at the University of California, San Francisco reviewed this study protocol and determined that this was not human research since we relied solely on published data.
Data sharing: Statistical code and dataset available from the corresponding author at:.
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