Indications of external radiotherapy for hepatocellular carcinoma from updated clinical guidelines: Diverse global viewpoints

Table 1 Categorization of evidences and recommendations of the clinical guidelines¹

Oxford system level of evidences2
1A	Systematic review of randomized clinical trials
1B	Individual RCTs with narrow confidence intervals
1C	All or none studies
2A	Systematic reviews of cohort studies
2B	Individual cohort study including low-quality RCTs
2C	Outcomes research; ecological studies
3A	Systematic review of case-control studies
3B	Individual case-control studies
4	Case series and poor-quality cohort and case-control studies
5	Expert opinion without explicit critical appraisal or descriptive epidemiology
GRADE system3
Quality of evidence criteria
High	(1) Further research is unlikely to change confidence in the estimate of the clinical effect.
Moderate	(2) Further research may change confidence in the estimate of the clinical effect.
Low	(3) Further research is very likely to impact confidence on the estimate of clinical effect.
Strength of recommendation criteria
Strong	(1) Factors influencing the strength of the recommendation included the quality of the evidence, presumed patient-important outcomes, and cost.
Weak	(2) Variability in preferences and values, or more uncertainty. Recommendation is made with less certainty, higher cost, or resource consumption.
NCCN categories of evidence and consensuses4
Category 1	Based upon high-level evidence, there is uniform NCCN consensus that the intervention is appropriate.
Category 2A	Based upon lower-level evidence, there is uniform NCCN consensus that the intervention is appropriate.
Category 2B	Based upon lower-level evidence, there is uniform NCCN consensus that the intervention is appropriate.
Category 3	Based upon any level of evidence, there is major NCCN disagreement that the intervention is appropriate.

¹Most clinical guidelines used their simplified adaptation of Oxford and GRADE system; above are selected examples.

²Data from clinical guidelines by Canadian Association for the Study of the Liver.

³Data from clinical guidelines by Korean Liver Cancer Study Group.

⁴Data from the NCCN formal website (Available from: https://www.nccn.org/professionals/physician_gls/categories_of_consensus.aspx). RCT: Randomized controlled trials; NCCN: National Comprehensive Cancer Network.