Evolution in the Presence and Evidence Category of Radiation Therapy Treatment Recommendations in the National Comprehensive Cancer Network Clinical Practice Guidelines in Oncology

PURPOSE: The changes in the recommended use of radiation therapy (RT) in the presence of expanding systemic cancer therapies and technological advances are poorly characterized. We sought to understand the recommended utilization of RT across a broad range of malignancies by examining National Comprehensive Cancer Network (NCCN) Guidelines. METHODS AND MATERIALS: We conducted a comprehensive review and categorization of RT recommendations, with their subsequent supporting evidence categories, in 3 versions of NCCN Guidelines, specifically years 2000, 2009, and 2019. These NCCN Guidelines were individually examined for RT-specific recommendations among the 10 most common tumors. The presence of RT as a recommended modality was recorded for each tumor type in each guideline. Recommendation categories including Category 1, 2A, 2B, and 3 were tallied and compared with examine totals and percentage distributions in each tumor type. RESULTS: A total of 3858 NCCN recommendations were individually reviewed. The presence of a recommendation inclusive of RT increased from incidence of 205 in the year 2000 to 992 in the year 2019 (383%). In the 2019 NCCN Guidelines, the most Category 1 RT recommendations were found within small cell lung (13%), non-small cell lung (5%), breast (5%), bladder (2%), rectal (2%), and non-Hodgkin lymphoma (1%). Pancreatic, uterine, prostate, melanoma, kidney, and colon cancer guidelines had no Category 1 RT recommendations. Rectal cancer had 31 (27%) preferred recommendations. The majority (89%) of 2019 RT recommendations were for initial therapy, and 9% were specific to salvage therapy. Tumor sites with the highest proportion of RT Category 1 evidence were small cell lung (29%), non-small cell lung (24%), and breast cancer (24%). CONCLUSIONS: The frequency of recommendations for using RT in NCCN Guidelines has increased by >300% in the past 20 years among the 10 most common malignancies. Consideration of the quality of evidence supporting these recommendations by tumor type is useful to identify specific malignancies in need of higher-level evidence supporting the role of RT.