Radiation Therapy Research: A Global Analysis 2001-2015.

Radiation therapy is a core modality of cancer treatment; however, concerns have been expressed regarding its underutilization and its lack of prioritization as a research domain relative to other cancer treatment modalities, despite its rapid technical evolution. It is therefore important to understand, from a public policy perspective, the evolution of global radiation therapy research, to identify strengths, weaknesses, and opportunities. This study used a bibliometric approach to undertake a quantitative analysis of global radiation therapy research published between 2001 and 2015 and available in the Web of Science (Wos) database, with particular focus on the 25 leading research-active countries. A total of 62,550 radiation therapy research articles from 127 countries, published in 2531 international journals, were analyzed. The United States was responsible for 32.3% of these outputs, followed by Japan (8.0%) and Germany (7.7%). Nearly half of all publications related to preparation and delivery of radiation therapy, combined-modality regimens, and dose fractionation studies. Health services research, palliative care, and quality of life studies represented only 2%, 5%, and 4% of all research outputs, respectively. Countries varied significantly in their commitment to different research domains, and trial-related publications represented only 5.1% of total output. Research impact was analyzed according to 3 different citation scores, with research outputs from Denmark, The Netherlands, and the United States consistently the highest ranked. Globally, radiation therapy publication outputs continue to increase but lag behind other spheres of cancer management. The types of radiation therapy research undertaken appear to be regionally patterned, and there is a clear disconcordance between the volume of research output from individual countries and its citation impact. Greater support for radiation therapy research in low- and middle-income countries is required, including international collaboration. The study findings are expected to provide the requisite knowledge to guide future radiation therapy research programs.