Estimating the optimal radiotherapy utilisation rate based on clinical guidelines and best available evidence and comparing it to current practice

It has previously been suggested that approximately 50% of all cancer patients should receive radiation. However, this estimate is not evidence-based. To estimate the ideal proportion of new cases of cancer that should receive external beam radiotherapy at least once during the course of their illness based on the best available evidence, and develop a model of radiotherapy utilisation that is useful for future changes in cancer incidence, stage at presentation and indications for radiotherapy. A systematic review of international guidelines on the treatment of cancers of the specific tumour-sites was undertaken. An optimal radiotherapy utilisation tree was constructed, depicting the indications for radiotherapy at various stages of cancer. The proportion of patients with clinical attributes that indicated a benefit from radiotherapy was obtained by inserting epidemiological data into the radiotherapy utilisation tree. The optimal proportion of patients with cancer that should receive radiotherapy was then calculated using TreeAge software The proportion of cancer patients in whom external beam radiotherapy is indicated was calculated to be 53% of all cancer. This estimate includes the following recommended optimal radiotherapy utilisation rates for the commonest cancers - breast 83%, lung 76%, prostate 60%, rectum 61%, melanoma 23% and gynaecological cancer 31%. Ideal utilisation rates for each cancer were compared with the published utilisation rates of radiotherapy in Australia and internationally over the last decade. Significant differences were found between the evidence-based recommended radiotherapy utilisation rate and the actual rates reported in clinical practice particularly for rectal and prostate cancer. This methodology allows comparison of optimal rates with actual rates to identify areas where improvements in the evidence-based use of radiotherapy can be made and provides valuable data for radiotherapy service planning