Level of Scientific Evidence Underlying Recommendations from the National Comprehensive Cancer Network (NCCN) Clinical Practice Guidelines for Hematologic Malignancies: Are We Moving Forward?

Background: National Comprehensive Cancer Network (NCCN) guidelines are the most comprehensive and widely used standard for clinical care in malignant hematology by clinicians and payers in the US. The level of scientific evidence in NCCN guidelines for malignant hematological conditions has not been recently 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.

Methods: NCCN uses a system of guideline development distinct from other major professional organizations. The NCCN definitions for EC are: category I, high level of evidence such as randomized controlled trials 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. We compared our results with previously published results from 2011 guidelines.

Results: Total recommendations increased by 16.6% from 1160 (2011) to 1353 (2020). Of the 1353 recommendations, Category 1, 2A, 2B and 3 EC were 5%, 91%, 4%, 1% while in 2011 they were 3%, 93%, 4% and 0% respectively. Recommendations with category 1 EC were found in all guidelines, except for Burkitt’s Lymphoma. 6.3% of therapeutic recommendations were category 1 EC with the majority (56.4%) pertaining to initial therapy. Guidelines with highest proportions of therapeutic recommendations with category 1 EC were Multiple Myeloma (12.4%), CLL/SLL (6.9%) and AML (5.6%). Between 2011 and 2020, the proportion of category I recommendations increased significantly only in Follicular lymphoma and CLL/SLL. No category 1 EC recommendations existed in staging or surveillance.

Conclusion: Recommendations issued in the 2020 NCCN guidelines are largely developed from lower levels of evidence but with uniform expert opinion. Despite the major advances in hematology in the past decade, this is largely unchanged. Our study underscores the urgent need and available opportunities to expand the current evidence base in malignant hematological disorders which forms the platform for clinical practice guidelines.