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problem of a slow rate of diffusion of innovation of cancer care, but optimal levels of use of each intervention are not known. One factor that might account for some of the underuse is possible underreporting of treatments in the Surveillance, Epidemiology, and End Results Program (SEER) cancer registry data (see description of SEER Program below).
BOX 4.1Levels of Evidence Applied to Clinical Research
The "hierarchy of evidence" applied to clinical research (i.e., when the question is whether a given treatment is effective in patients with a specific type of cancer) is well established and agreed upon. The following version is taken from the Well-respected U.S. Preventive Services Task Force, proceeding from the most reliable to the least reliable type of evidence (i.e., from grade I to grade III):
I
Evidence obtained from at least one properly randomized controlled trial.
II-1
Evidence obtained from well-designed controlled trials without randomization.
II-2
Evidence obtained from well-designed cohort or case-control (epidemiologic) studies.
II-3
Evidence obtained from multiple time series. with or without the intervention—dramatic results in uncontrolled experiments (e.g., the results of the introduction of penicillin treatment in the 1940s) could also be regarded as this type of evidence.
III
Opinions of respected authorities, based on clinical experience, descriptive studies and case repeals, or repeals of expert committees.
SOURCE: U.S. Department of Health and Human Services, 1996.
