Risk of Bias and Quality of Reporting in Colon and Rectal Cancer Systematic Reviews Cited by National Comprehensive Cancer Network Guidelines

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Introduction: Given the changing landscape of colorectal cancer, systematic reviews are likely to play a key role in advancing the understanding of prevention, diagnosis, and treatment. Methods: We conducted a cross-sectional investigation of the risk of bias and reporting quality of systematic reviews referenced by colon and rectal cancer National Comprehensive Cancer Network (NCCN) guidelines. We used two widely accepted tools: Risk of Bias in Systematic reviews (ROBIS) and Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA). Results: Using ROBIS, only 3 (4.8%) systematic reviews were judged with low risk of bias, 35 (55.6%) systematic reviews were judged with unclear risk of bias, and 25 (39.7%) systematic reviews were judged with high risk of bias. Across all systematic reviews, the individual bias domains at the highest risk of bias were domains 1 (protocol and eligibility criteria) and 2 (methods to identify and select studies). Across all studies, the median adherence to PRISMA was 74.1% (IQR 69.2–80.0%), corresponding to approximately 20 of 27 items. Conclusions: Systematic reviews cited in NCCN guidelines for colon and rectal cancer are frequently at unclear or high risk of bias and do not report key systematic review items that are important for the critical appraisal of results.

Original languageEnglish
JournalJournal of General Internal Medicine
StateAccepted/In press - 1 Jan 2020



  • bias
  • colon cancer
  • oncology
  • rectal cancer
  • systematic review

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