Levels of Evidence for Radiation Therapy Recommendations in the National Comprehensive Cancer Network (NCCN) Clinical Guidelines

ABSTRACT PURPOSE The National Comprehensive Cancer Network (NCCN) clinical guidelines influence medical practice, payor coverage and standards of care. The levels of evidence underlying radiotherapy recommendations in NCCN have not been systematically explored. Herein, we aim to systematically investigate the NCCN recommendations pertaining to the categories of consensus and evidence (CE) for radiotherapy. METHODS We evaluated the distribution of CE underlying current treatment recommendations for the 20 most prevalent cancers in the United States with at least 10 radiotherapy recommendations in the NCCN clinical guidelines. For context, the distribution of evidence in the radiation therapy guidelines was compared with that of systemic therapy using a chi-square test. The proportion of category I CE between radiation and systemic therapy was compared using a two-proportion, two-tailed Z-test in total and for each disease site. A p-value of RESULTS Among all radiotherapy recommendations, the proportions of category I, IIA, IIB, and III CE were 9.7%, 80.6%, 8.4%, and 1.3%, respectively. When analyzed by disease site, cervix and breast cancer had the highest portion of category I CE (33% and 31%, respectively). There was no radiotherapy category I CE for hepatobiliary, bone, pancreatic, melanoma, and uterine cancers. There was a significant difference in the distribution of CE between the systemic therapy recommendations and the radiotherapy recommendations (chi-square statistic 64.16, p CONCLUSION Only 9.7% of radiotherapy recommendations in NCCN guidelines are category I CE. The highest levels of evidence for radiotherapy are in breast and cervical cancers. Despite major advances in the field, these data underline that the majority of NCCN radiotherapy recommendations are based on uniform expert opinion and not on higher level evidence.