Level of Scientific Evidence Underlying Recommendations Arising From the National Comprehensive Cancer Network Clinical Practice Guidelines for Hematologic Malignancies

The level of scientific evidence on which the National Comprehensive Cancer Network (NCCN) guidelines are based has not been systematically investigated. We describe the distribution of categories of evidence and consensus (EC) among the 10 most common hematologic malignancies with regard to recommendations for staging, initial and salvage therapy, and surveillance.

NCCN uses a system of guideline development distinct from other major professional organizations. The NCCN definitions for EC are as follows: category I, high level of evidence with uniform consensus; category IIA, lower level of evidence with uniform consensus; category IIB, lower level of evidence without a uniform consensus but with no major disagreement; and category III, any level of evidence but with major disagreement.

Of the 1160 recommendations found in the 10 guidelines, the proportions of category I, IIA, IIB, and III EC were 3%, 93%, 4%, and 0%, respectively. Recommendations with category I were found in acute myeloid leukemia (4%), multiple myeloma (7%), Hodgkin's lymphoma (1%), diffuse large B-cell lymphoma (4%), follicular lymphoma (11%). Chronic lymphocytic leukemia/small lymphocytic lymphoma, mantle cell lymphoma, marginal zone lymphoma, AIDS-related B-cell lymphoma, and Burkitt lymphoma did not have any category I recommendations. Three percent of all therapeutic recommendations were category I. Guideline with the highest proportion of category I therapeutic recommendations was for diffuse large B-cell lymphoma (46%). No category I recommendations were found on staging or surveillance.

Recommendations issued in the NCCN guidelines are largely developed from lower levels of evidence but with uniform expert opinion. This underscores the urgent need and available opportunities to expand evidence base in oncology.

No relevant conflicts of interest to declare.