Background: We have previously quantified the evidence-based optimal (Barton 2013) radiotherapy use but the factors that influence the actual use of radiotherapy are not well identified.
Aims: To estimate the actual radiotherapy utilisation (RTU) rate in NSW, identify the influencing factors, compare the actual versus optimal rates from evidence-based models and quantify the shortfall effects on patient outcomes at the population level.
Methods: Actual RTU rates for Breast, Colorectal cancers, Melanoma defined as 'proportion of patients treated with radiotherapy within one year of diagnosis over all patients diagnosed with that condition' in NSW (2009-2011) were quantified from Central Cancer Registry data linked with radiotherapy service data. Factors affecting RTU were identified through logistic regression analyses. Shortfalls from the optimal proportions for the guidelines-recommended indications that require radiotherapy were estimated and the corresponding local control (LC) and overall survival (OS) benefit shortfalls in person numbers were assessed. Estimates of radiotherapy benefit were obtained from published benefit models developed in the setting of optimal use (Hanna/Shafiq 2017).
Results: Actual RTU rates during 2009-2011 have not reached the recommended optimal rates for breast cancer (59% vs 88%), rectal cancer (34% vs 55%) and melanoma (4% vs 15%) whereas for colon cancer the rates were similar (4%). Significant (p<0.05) predicting factors for lower actual RTU were older age, tumour stage, and longer travelling distance to the nearest treatment facility. The number of cases with a loss of LC or OS at 5 years due to under-use of radiotherapy were: breast (LC 652, OS 87), rectal (LC 180, OS 55), and melanoma (LC 276).
Conclusion: Our study highlighted that under-utilisation of radiotherapy is still evident in NSW. This has direct effects on patient outcomes that require addressing. Factors that predict for lower use will assist future strategies to address shortfall in evidence-based care