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Screening for Breast Cancer

A Systematic Review to Update the 2009 U.S. Preventive Services Task Force Recommendation

Evidence Syntheses, No. 124

Investigators: , MD, MPH, , MD, MPH, , MD, MPH, , PhD, , MA, , BA, and , MS.

Author Information
Rockville (MD): Agency for Healthcare Research and Quality (US); .
Report No.: 14-05201-EF-1

Structured Abstract

Background:

In 2009, the U.S. Preventive Services Task Force (USPSTF) recommended biennial screening mammography for women age 50 to 74 years, and based decisions for earlier screening on individual patient context and values. Evidence was insufficient to recommend screening beyond age 75.

Purpose:

To systematically update the 2009 USPSTF review on screening for breast cancer in average risk women age 40 years and older.

Data Sources:

The Cochrane Central Register of Controlled Trials and Cochrane Database of Systematic Reviews (through December 2014), Ovid MEDLINE (through December 2014), and reference lists were searched for relevant studies. Additional data were obtained from investigators of randomized trials and from the Breast Cancer Surveillance Consortium.

Study Selection:

Randomized controlled trials and observational studies of breast cancer screening in asymptomatic women age 40 and older reporting breast cancer mortality, all-cause mortality, advanced breast cancer, treatment morbidity, and the harms of screening.

Data Extraction:

One investigator abstracted data and a second investigator confirmed accuracy. Investigators independently dual-rated study quality and applicability using established criteria. Discrepancies were resolved through a consensus process.

Data Synthesis:

A meta-analysis of screening trials with updated data from the Canadian (CNBSS-1 and CNBSS-2), Swedish Two-County Study, and Age trials indicated breast cancer mortality reductions for age 39 to 49 years (relative risk [RR] 0.88; 95% confidence interval [CI], 0.73 to 1.003; 9 trials; 4 deaths prevented/10,000 over 10 years); 50 to 59 years (RR 0.86 [95% CI, 0.68 to 0.97]; 7 trials; 8/10,000); 60 to 69 years (RR 0.67 [95% CI, 0.54 to 0.83]; 21/10,000); and 70 to 74 years (RR 0.80 [95% CI, 0.51 to 1.28]; 3 trials; 13/10,000). Risk reduction was 25 to 31 percent for women age 50 to 69 years across several observational studies, with similar reductions for women age 40 to 49 in two studies. Trials indicated no statistically significant reductions in all-cause mortality with screening. Risk for higher-stage breast cancer was reduced for age 50 years and older (RR 0.62 [95% CI, 0.46 to 0.83]; 3 trials), but not for age 39 to 49 years (RR 0.98 [95% CI, 0.74 to 1.37]; 4 trials). The majority of cases from screening were ductal carcinoma in situ and early stage, and screening resulted in more mastectomies (RR 1.20 [95% CI, 1.11 to 1.30]; 5 trials) and radiation (RR 1.32 [95% CI, 1.16 to 1.50]; 2 trials).

Younger women and those with risk factors had more false-positive results and recommendations for additional imaging and biopsies. Cumulative rates for false-positive mammography results over 10 years were 61 percent for annual and 42 percent for biennial screening; rates for biopsy were 7 to 9 percent for annual and 5 to 6 percent for biennial screening. Estimates of overdiagnosis ranged from 11 to 22 percent in trials; and 1 to 10 percent in observational studies. Some women with false-positive results or pain experienced distress and were less likely to return for their next mammogram. Tomosynthesis with mammography reduced recalls (16/1000), but increased biopsies (1.3/1000) and cancer detection (1.2/1,000). The number of deaths due to radiation induced cancer from screening with digital mammography was estimated through modeling as between 2 to 11 per 100,000 depending on age at onset and screening intervals.

Limitations:

Limited to English-language articles; the number, quality, and applicability of studies varied widely. Trials of mammography screening reflect imaging technologies and cancer treatment therapies that are not currently in use. Studies are lacking on screening effectiveness based on risk factors, intervals, and modalities; and on screening modalities relevant to women who are not high-risk.

Conclusions:

Breast cancer mortality is reduced with mammography screening, although estimates are of borderline statistical significance, the magnitudes of effect are small for younger ages, and results vary depending on how cases were accrued in trials. Higher stage tumors are also reduced with screening for age 50 years and older. False-positive results are common in all age groups, and are higher for younger women and those with risk factors. Approximately 11 to 22 percent of cases may be overdiagnosed. Observational studies indicate that tomosynthesis with mammography reduces recalls, but increases biopsies and cancer detection. Mammography screening at any age is a tradeoff of a continuum of benefits and harms.

Contents

Acknowledgements: The authors acknowledge Andrew Hamilton, MLS, MS, for conducting literature searches and Spencer Dandy, BS, for assistance with drafting this report at the Oregon Health & Science University; and Alison Conlin, MD, MPH, and Michael Neuman, MD, at the Providence Cancer Center, and Arpana Naik, MD, at the Oregon Health & Science University for medical expertise. The authors also thank the AHRQ Medical Officer, Jennifer Croswell, MD, MPH, and Tess Miller, DrPH, as well as current and former members of the U.S. Preventive Services Task Force who contributed to topic deliberations.

Data collection was supported by the National Cancer Institute-funded Breast Cancer Surveillance Consortium (BCSC) (HHSN-261-2011-00031-C, P01CA154292, and U54CA163303). Cancer data collection was supported in part by State public health departments and cancer registries in the United States (http:​//breastscreening​.cancer.gov/work/acknowledgement.html). The authors thank the BCSC investigators and participating women, mammography facilities, and radiologists for the data they provided for this work, and especially Diana Miglioretti, PhD, Ellen O'Meara, PhD, and Steven Balch of the BCSC Statistical Coordinating Center for providing information and analyses.

Prepared for: Agency for Healthcare Research and Quality, U.S. Department of Health and Human Services1. Contract No. HHSA-290-2012-00015-I, Task Order No. 2. Prepared by: Pacific Northwest Evidence-based Practice Center2

Suggested citation:

Nelson HD, Cantor A, Humphrey L, Fu R, Pappas M, Daeges M, Griffin J. Screening for Breast Cancer: A Systematic Review to Update the 2009 U.S. Preventive Services Task Force Recommendation. Evidence Synthesis No. 124. AHRQ Publication No. 14-05201-EF-1. Rockville, MD: Agency for Healthcare Research and Quality; 2016.

This report is based on research conducted by the Pacific Northwest Evidence-based Practice Center (EPC) under contract to the Agency for Healthcare Research and Quality (AHRQ), Rockville, MD (Contract No. HHSA-290-2012-00015-I, Task Order No. 2). The findings and conclusions in this document are those of the authors, who are responsible for its contents, and do not necessarily represent the views of AHRQ. Therefore, no statement in this report should be construed as an official position of AHRQ or of the U.S. Department of Health and Human Services.

The information in this report is intended to help health care decisionmakers—patients and clinicians, health system leaders, and policymakers, among others—make well-informed decisions and thereby improve the quality of health care services. This report is not intended to be a substitute for the application of clinical judgment. Anyone who makes decisions concerning the provision of clinical care should consider this report in the same way as any medical reference and in conjunction with all other pertinent information (i.e., in the context of available resources and circumstances presented by individual patients).

This report may be used, in whole or in part, as the basis for development of clinical practice guidelines and other quality enhancement tools, or as a basis for reimbursement and coverage policies. AHRQ or U.S. Department of Health and Human Services endorsement of such derivative products may not be stated or implied.

None of the investigators has any affiliations or financial involvement that conflicts with the material presented in this report.

1

5600 Fishers Lane, Rockville, MD 20857; www​.ahrq.gov

2

Oregon Health & Science University, Mail Code: BICC, 3181 SW Sam Jackson Park Road, Portland, OR 97239

Bookshelf ID: NBK343819PMID: 26889531

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