The evidence base for breast cancer screening

Centre for Research in Evidence-Based Practice, Bond University, Gold Coast, 4229 Australia.
Preventive Medicine (Impact Factor: 3.09). 06/2011; 53(3):100-2. DOI: 10.1016/j.ypmed.2011.05.011
Source: PubMed


The history of breast cancer screening is littered with controversy. With 10 trials spanning 4 decades, we have a substantial body of evidence, but with different aims and flaws. Combined analysis of the intention-to-treat results gives an overall relative reduction in breast cancer mortality of 19% (95% CI 12%-26%), which, if adjusted for non-attendance gives an approximate 25% relative reduction for those who attend screening. However, given that 4% of all-cause mortality is due to breast cancer deaths, this translates into a less than 1% reduction in all-cause mortality. An emerging issue in interpretation is the improvements in treatment since these trials recruited women. Modern systemic therapy would have improved survival (models suggest between 12% and 21%) in both screened and non-screened groups, which would result in a lesser difference in absolute risk reduction from screening but probably a similar, or slightly smaller, relative risk reduction. However benefits and harms, particularly over-diagnosis, need to balanced and differ by age-groups. The informed views of recipients of screening are needed to guide current and future policy on screening.

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    • "Mammography is the only breast cancer-screening test shown in randomized trials to be associated with reduced breast cancer mortality [1] [2]. However, despite progressive technological refinements , and improvements in quality since the implementation of the Mammography Quality Standards ACT of 1992 [3], extensive variability in interpretive performance of screening mammography has been reported [4] [5]. "
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    ABSTRACT: We examined interpretive efficiency and variability in true- and false-positive detection (TP, FP) for radiologists screen-reading with digital breast tomosynthesis as adjunct to full-field digital mammography (2D/3D) relative to 2D alone in population-based screening studies. A systematic literature search was performed to identify screening studies that provided radiologist-specific data for TP and FP detection. Radiologist interpretive efficiency (trade-off between TPs and FPs) was calculated using the FP:TP ratio which expresses the number of FP recalls for each screen-detected breast cancer. We modeled a pooled FP:TP ratio to assess variability in radiologists' interpretive efficiency at study-level using random effects logistic regression. FP:TP ratio improved (ratio decreased) for 2D/3D screen-reading (relative to 2D) for a majority of radiologists (18 of 22) across all studies. Variability in radiologists' FP:TP ratio was consistently lower in all studies for 2D/3D screen-reading, as suggested by lower variance in ratios. Study-level pooled FP:TP ratio for 2D- and 2D/3D-mammography respectively, were 5.96 (95%CI: 4.08 to 8.72) and 3.17 (95%CI: 2.25 to 4.47) for the STORM trial; 10.25 (95%CI: 6.42 to 16.35) and 7.07 (95%CI: 4.99 to 10.02) for the Oslo trial; and 20.84 (95%CI: 13.95 to 31.12) and 8.37 (95%CI: 5.87 to 11.93) for the Houston study. This transfers into study-level improved interpretative efficiencies of 48%, 30% and 55%, respectively, for 2D/3D screen-reading (relative to 2D). In summary, study-level FP:TP trade-off improved using 2D/3D-mammography for all studies, which was also seen for most individual radiologists. There was variability in the FP:TP trade-off between readers and studies for 2D-as well as for 2D/3D-interpretations but variability in radiologists' interpretive efficiency was relatively lower using 2D/3D-mammography.
    The Breast 09/2015; DOI:10.1016/j.breast.2015.08.012 · 2.38 Impact Factor
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    • "mammographic screening are determined by international organizations and differ in every country according to their own standards dependent on screening policies. The randomized controlled trials and observational studies of screening programs have shown the efficacy of mammographic screening in women aged 50-69 years (Glasziou and Houssami, 2011). In almost all countries outside the USA, screening programs start at 50 years of age. "
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    ABSTRACT: Background: The Bahcesehir Breast Cancer Screening Project is the first organized population based breast cancer mammographic screening project in Turkey. The objective of this prospective observational study was to demonstrate the feasibility of a screening program in a developing country and to determine the appropriate age (40 or 50 years old) to start with screening in Turkish women. Materials and methods: Between January 2009 to December 2010, a total of 3,758 women aged 40-69 years were recruited in this prospective study. Screening was conducted biannually, and five rounds were planned. After clinical breast examination (CBE), two-view mammograms were obtained. True positivity, false positivity, positive predictive values (PPV) according to ACR, cancer detection rate, minimal cancer detection rate, axillary node positivity and recall rate were calculated. Breast ultrasound and biopsy were performed in suspicious cases. Results: Breast biopsy was performed in 55 patients, and 18 cancers were detected in the first round. The overall cancer detection rate was 4.8 per 1,000 women. Most of the screened women (54%) and detected cancers (56%) were in women aged 40- 49. Ductal carcinoma in situ (DCIS) and stage I cancer and axillary node positivity rates were 22%, 61%, and 16.6%, respectively. The positive predictivity for biopsy was 32.7%, whereas the overall recall rate was 18.4 %. Conclusions: Preliminary results of the study suggest that population based organized screening are feasible and age of onset of mammographic screening should be 40 years in Turkey.
    Asian Pacific journal of cancer prevention: APJCP 02/2014; 15(4):1693-1697. DOI:10.7314/APJCP.2014.15.4.1693 · 2.51 Impact Factor
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    • "Mammography screening has been shown to reduce breast cancer mortality in overviews of the randomised trials, and both its benefits and harms have been evaluated and debated [1] [2] [3]. Recently, two prospective population-based screening trials [4] [5] have shown that adding digital breast tomosynthesis or 3D-mammography, a derivative mammographic technology [6] [7] [8] [9], to conventional 2D-mammography significantly increases breast cancer detection. "
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    ABSTRACT: Purpose We compared detection measures for breast screening strategies comprising single-reading or double-reading using standard 2D-mammography or 2D/3D-mammography, based on the ‘screening with tomosynthesis or standard mammography’ (STORM) trial. Methods STORM prospectively examined screen-reading in two sequential phases, 2D-mammography alone and integrated 2D/3D-mammography, in asymptomatic women participating in Trento and Verona (Northern Italy) population-based screening services. Outcomes were ascertained from assessment and/or excision histology or follow-up. For each screen-reading strategy we calculated the number of detected and non-detected (including interval) cancers, cancer detection rates (CDRs), false positive recall (FPR) measures and incremental CDR relative to a comparator strategy. We estimated the false:true positive (FP:TP) ratio and sensitivity of each mammography screening strategy. Paired binary data were compared using McNemar’s test. Results Amongst 7292 screening participants, there were 65 (including six interval) breast cancers; estimated first-year interval cancer rate was 0.82/1000 screens (95% confidence interval (CI): 0.30–1.79/1000). For single-reading, 35 cancers were detected at both 2D and 2D/3D-mammography, 20 cancers were detected only with 2D/3D-mammography compared with none at 2D-mammography alone (p < 0.001) and 10 cancers were not detected. For double-reading, 39 cancers were detected at 2D-mammography and 2D/3D-mammography, 20 were detected only with 2D/3D-mammography compared with none detected at 2D-mammography alone (p < 0.001) and six cancers were not detected. The incremental CDR attributable to 2D/3D-mammography (versus 2D-mammography) of 2.7/1000 screens (95% CI: 1.6–4.2) was evident for single and for double-reading. Incremental CDR attributable to double-reading (versus single-reading) of 0.55/1000 screens (95% CI: −0.02–1.4) was evident for 2D-mammography and for 2D/3D-mammography. Estimated FP:TP ratios showed that 2D/3D-mammography screening strategies had more favourable FP to TP trade-off and higher sensitivity, applying single-reading or double-reading, relative to 2D-mammography screening. Conclusion The evidence we report warrants rethinking of breast screening strategies and should be used to inform future evaluations of 2D/3D-mammography that assess whether or not the estimated incremental detection translates into improved screening outcomes such as a reduction in interval cancer rates.
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