Estimating the optimal radiotherapy utilization for carcinoma of the central nervous system, thyroid carcinoma, and carcinoma of unknown primary origin from evidence-based clinical guidelines

BACKGROUND. In this one in a series of articles, the objective was to estimate the ideal proportion of patients with cancer who should receive radiotherapy at least once during the course of their illness based on the best available evidence. This estimate Should be useful in planning for future radiotherapy facilities. Optimal rates of radiotherapy for patients with central nervous system (CNS) carcinoma, thyroid carcinoma, or carcinoma of unknown primary site (CUP) have not been studied previously. METHODS. A systematic review of evidence-based treatment guidelines for the treatment of CNS carcinoma, CUP, and thyroid carcinoma was undertaken. An optimal radiotherapy utilization tree was constructed for each of these malignancies depicting the indications for radiotherapy at various stages of disease. The proportion of patients who had clinical attributes that indicated a possible benefit from radiotherapy was calculated by adding epidemiological data to the radiotherapy utilization tree. The optimal proportion of patients who should receive radiotherapy was then calculated using specialized decision-analysis software. Sensitivity analyses using univariate analysis and Monte Carlo simulations were performed. RESULTS. The optimal rates of radiotherapy utilization for carcinoma of the CNS, thyroid carcinoma, and CUP were 92%, 10%, and 61%, respectively. Comparison with actual rates of utilization in South Australia, Sweden, and the U.S. suggested an under-utilization of radiotherapy for CNS carcinoma and CUP. However, the actual rates of radiotherapy for thyroid carcinoma exceeded the optimal rate for some jurisdictions, although some data may have included radioactive iodine, which was not included in the current project. CONCLUSIONS. It was possible to estimate optimal radiotherapy utilization rates based on evidence. This methodology allowed a comparison of optimal rates with actual rates to identify areas in which improvements in the evidence-based use of radiotherapy can be made, and it may provide valuable data for future. radiotherapy service planning.