Level 1: High Strength/Quality
or
Evidence consisting of a non-blinded or single-blinded trial that meets study objective end points may be considered as Level 1 evidence in some cancer-related cases (e.g., NCI-sponsored cooperative group study or a multicenter trial).
Level 2: Moderate Strength/Quality
Evidence consisting of a non-blinded, non-randomized trial (e.g., a phase II study) may be considered as Level 2 evidence in some cancer-related cases (e.g., rare cancers or cancers with limited available treatment options).
Level 3: Low Strength/Quality
Level 4: Opinion/Experience
(listed in descending order)
Recommended (Accepted) The drug or biologic should be used, is recommended/indicated, or is useful/effective/beneficial in most cases.
Reasonable Choice (Accepted, with Possible Conditions) (e.g., treatment option) The drug or biologic is reasonable to use under certain conditions (e.g., in certain patient groups), can be useful/effective/beneficial, or is probably recommended or indicated.
Not Fully Established (Unclear Risk/Benefit, Equivocal Evidence, Inadequate Data and/or Experience) Usefulness and/or effectiveness is unknown, unclear, or uncertain or is not well established relative to the standard of care.
Not Recommended (Unaccepted) The drug or biologic is considered inappropriate, obsolete, or unproven; is not recommended, is not indicated, or is not useful/effective/beneficial; or may be harmful.