Laura Rees Willett, MD, FACP
Does mammography screening reduce breast cancer mortality in woman 40 to 49 years of age or > 69 years of age? Does clinical breast examination (CBE) or breast self-examination (BSE) reduce breast cancer mortality? What are the harms of screening?
Included studies evaluated breast cancer screening with mammography, CBE, or BSE in women without preexisting breast cancer and at average risk for breast cancer. Outcomes included breast cancer mortality and screening harms (e.g., diagnosis of abnormal lesions unlikely to become clinically evident [overdiagnosis]).
MEDLINE (2001 to 2008), Cochrane Central Register of Controlled Trials and Cochrane Database of Systematic Reviews (Issue 4, 2008), Web of Science, and reference lists were searched for randomized controlled trials (RCTs) published or updated after 2001. Good-quality systematic reviews and meta-analyses and subsequently published primary studies were considered for evaluation of harms. 8 RCTs of mammography (n = 556 907), 2 RCTs of BSE (n = 389 812), and 4 RCTs of CBE (n not reported) were included for evaluation of effectiveness.
Mammography. Meta-analysis showed that mammography screening reduced breast cancer mortality more than usual care in women 39 to 49 years of age and those 50 to 69 years of age (Table). 1 RCT found that mammography did not reduce breast cancer mortality in women > 69 years of age (Table). Based on 5 RCTs, the absolute excess cumulative incidence of invasive and in situ breast cancer attributed to overdiagnosis was 0.07 to 0.73 per 1000 woman-years with mammography. CBE. 1 RCT found that CBE alone or with mammography did not differ for breast cancer mortality (data not reported). BSE. BSE instruction did not reduce breast cancer mortality in 1 RCT (Table) or all-cause mortality in 1 RCT (n = 123 748, relative risk increase [RRI] 7%, 95% CI −12 to 29). BSE instruction increased risk for benign biopsy in 2 RCTs (n = 266 064, RRI 57%, CI 48 to 68; n = 123 748, RRI 105%, CI 80 to 133).
In women 39 to 69 years of age, mammography screening reduces breast cancer mortality, with most benefit in those 60 to 69 years of age. CBE and BSE do not reduce mortality.
Breast cancer screening vs usual care for breast cancer mortality in women*
*BSE = breast self-examination; CrI = credible interval; NNS = number needed to invite for screening; NR = not reported; other abbreviations defined in Glossary. RRR, RRI, NNS, CrI, and CI calculated from data in article using a random-effects model and Bayesian analytic framework for pooled data.
Willett LR. Review: In women 39 to 69 years of age, screening with mammography reduces breast cancer mortality. Ann Intern Med. ;152:JC2–7. doi: 10.7326/0003-4819-152-4-201002160-02007
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Published: Ann Intern Med. 2010;152(4):JC2-7.
Breast Cancer, Hematology/Oncology.
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Print ISSN: 0003-4819 | Online ISSN: 1539-3704
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