CRD summary

This review concluded that within a routine screening programme, full-field digital mammography with hard-copy reading performed at least as well as screen-film mammography for breast cancer detection. Multiple issues with the methodology and reporting of the review process mean that the reliability of these conclusions is unclear.

Authors' objectives

To compare full-field digital mammography using hard-copy image reading with screen-film mammography within a three-yearly screening programme for women aged 50 years or over.

Searching

PubMed, MEDLINE and EMBASE were searched from January 2000 to February 2008 for studies published in English-language journals. Search terms were reported. References of relevant articles and reviews were checked. The authors' own study was included in the review.

Study selection

It appeared that studies that compared the diagnostic performance of full-field digital mammography using hard-copy image reading with screen-film mammography were eligible for inclusion. Studies were required to report detection rates, recall rates or positive predictive values of an abnormal mammogram according to screening modality. Studies in diagnostic populations were excluded from the review.

Included studies were conducted in USA, Canada, Norway, Japan, Italy and UK. Differences in equipment and details of techniques, which included single or double reading of images, were reported in the paper.

Two reviewers independently assessed studies for inclusion in the review.

Assessment of study quality

The authors did not state that they assessed validity.

Data extraction

Differences in outcomes were estimated together with 95% confidence intervals (CI) and differences in positive predictive values from paired studies were calculated. Where necessary, authors were contacted for additional information.

The authors did not state how many reviewers performed data extraction.

Methods of synthesis

Where possible, studies were combined using random-effects model meta-analyses with and without stratification by age (up to age 60 versus over 60 years). Statistical heterogeneity was assessed using Χ² and I² statistics. Publication bias was assessed using funnel plot analysis and the Egger test.

Results of the review

Eight studies were included in the review. Four studies had a prospective paired design (one of which used random allocation of order of tests). One study was a randomised controlled trial and three were cohort studies. Follow-up was one to two years in study designs, except for cohort studies where only detected cases were followed up.

The overall pooled estimate for differences in detection rate between full-field digital mammography and screen-film mammography was four (95% CI -3 to 11) extra breast cancers per 10,000 screening mammograms with some evidence of heterogeneity (I²=40%). Stratification of analyses by age showed higher full-field digital mammography detection rates for women aged up to 60 years with 11 (95% CI 4 to 18) extra breast cancers per 10,000 screening mammograms with no evidence of heterogeneity (I²=0%). Data on women aged over 60 was sparse, but one study found that while full-field digital mammography had higher detection rates among women under 50 with dense breasts, screen-film mammography had slightly higher rates in women aged over 64 with non-dense breasts.

There was too high a level of heterogeneity (I²=94%) in recall rates for data to be pooled; USA studies showed much higher levels than European or Japanese studies. There was also a high level of heterogeneity (I²=100%) for the positive predictive values of an abnormal mammogram; only cohort studies showed a higher positive predictive value for full-field digital mammography. Therefore, these outcomes were not combined statistically.

There was no evidence of publication bias.

Authors' conclusions

Within a routine screening programme, full-field digital mammography with hard-copy reading performed at least as well as screen-film mammography for breast cancer detection.

CRD commentary

The review question was clear. The supporting inclusion criteria were not well defined, except for outcomes. The authors searched two relevant databases, but the limitation of the review to published studies reported in English may have led to omission of relevant studies and introduction of language and publication biases. Publication bias was assessed, but such assessments are rarely informative where so few studies are involved. The authors reported using methods designed to reduce reviewer bias and error in study selection, but not in data extraction. Study validity was not assessed, which made it difficult to determine the reliability of the evidence on which the conclusions rested. Reasonable decisions based on an assessment of study comparability were made on where statistical synthesis of results was appropriate. The authors' conclusions reflected the results of the review, but multiple issues with the conduct and reporting of the review process mean that the reliability remains unclear.

Implications of the review for practice and research

Practice: The authors did not state any implications for practice.

Research: The authors stated that there was a need for research to assess the economic costs of full-field digital mammography and identify the best clinical and most cost-effective ways of implementation.

Funding

Not stated.

Bibliographic details

Vinnicombe S, Pinto Pereira SM, McCormack VA, Shiel S, Perry N, dos Santos Silva IM. Full-field digital versus screen-film mammography: comparison within the UK breast screening program and systematic review of published data. Radiology 2009; 251(2): 347-358. [PubMed: 19401569]

Original Paper URL

http://radiology.rsna.org/content/251/2/347.short

Indexing Status

Subject indexing assigned by NLM

MeSH

Breast Neoplasms /epidemiology /radiography; Female; Great Britain /epidemiology; Humans; Mammography /statistics & numerical data; Mass Screening /statistics & numerical data; Radiographic Image Enhancement; Reproducibility of Results; Sensitivity and Specificity; X-Ray Film /statistics & numerical data

AccessionNumber

12009105653

Database entry date

22/09/2010

Record Status

This is a critical abstract of a systematic review that meets the criteria for inclusion on DARE. Each critical abstract contains a brief summary of the review methods, results and conclusions followed by a detailed critical assessment on the reliability of the review and the conclusions drawn.