New research suggests that clinical guidelines for breast cancer are supported by systematic reviews of varying quality. 

Researchers analyzed reviews cited in 5 breast cancer guidelines and found that nearly half of the reviews were of “critically low” quality, according to an assessment tool.

These findings were published in Clinical Breast Cancer.

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The researchers examined 5 clinical practice guidelines developed by the National Comprehensive Cancer Network (NCCN) and the European Society for Medical Oncology (ESMO). The guidelines contained 1341 references and 69 unique systematic reviews.

The researchers assessed the methodological quality of reporting within the reviews using 2 tools — PRISMA and AMSTAR-2. PRISMA is a 27-item checklist, and AMSTAR-2 has 16 items. The researchers calculated completeness scores based on the proportion of criteria met for each tool.

The mean PRISMA score was 76.3%, and the mean AMSTAR-2 score was 66.5%. Cochrane systematic reviews were more likely to adhere to PRISMA (0.91 vs 0.74) and AMSTAR-2 (0.95 vs 0.62) compared with non-Cochrane reviews.

Overall, only 1 review adhered to all PRISMA items. The PRISMA items that were most often completed across the reviews were the summary of evidence in the discussion and the authors’ ability to specify study characteristics in the methods. The items that were least likely to be completed were the presence of a pre-established protocol in the methods and an assessment on the risk of bias within studies.

According to AMSTAR-2, 49% of the reviews were of “critically low” quality, and 10.2% were of “high quality.” The AMSTAR-2 items that were most commonly completed across the reviews were an explanation by the authors for the study designs they chose to include in the review and the inclusion of population, intervention, comparator group, and outcome criteria. The least frequently completed items were the sources of funding and reporting of a pre-established methods protocol. 

Based on these findings, the researchers advised that clinical practice guidelines “use a more standardized method to seek out evidence to establish their recommendations.”  

“We recommend a more uniform adoption of improved quality of reporting among systematic reviews cited within the ESMO and NCCN clinical practice guidelines,” the researchers wrote. “Improved reporting allows clinicians to have increased confidence in the guidelines, and thus increased utilization in clinical decision making.”


Snider K, Moore T, Walters C, et al. An analysis of the evidence informing clinical practice guidelines in the management and treatment of breast cancer. Clin Breast Cancer. Published online April 28, 2022.