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Abstract
Background: The population benefits achievable with optimal access to radiotherapy in Australia are unknown. This information would be of use for planning, priority setting, and economic analysis.
Methods: 5-year local control (LC) and 2-year and 5-year overall survival (OS) benefits were investigated for gynaecological, head and neck, genitourinary, thyroid and brain cancers. Benefits were determined for each radiotherapy indication, for each cancer, in an optimal radiotherapy utilization decision tree. Radiotherapy alone benefits were defined as the absolute benefit of radiotherapy over no treatment for radical indications, and of post-operative radiotherapy over surgery alone for adjuvant indications. These benefits were distinct from other modalities’ benefits. The incremental benefit of chemoradiation (CRT) over radiotherapy alone was also estimated. Pre-existing Australian radiotherapy demand models defining the incidence of each indication were adapted. TreeAge Pro 2008 software was utilized. A systematic review was performed to identify the highest level of evidence defining each indication benefit. Multiple Ovid electronic citation databases were queried (Medline, EMBase, Ovid EBM sources). Where there were multiple sources of the same evidence level, a meta-analysis was performed. Model robustness was tested through deterministic and probabilistic sensitivity analysis.
Results: 35% of all cancer patients had curative radiotherapy indications for cancer types considered. By cancer type, the radiotherapy alone LC benefit ranged from 1.0% (thyroid) to 76% (nasopharynx); for 5-year OS 0.2% (lip) to 59% (nasopharynx). The additional benefit of CRT over radiotherapy alone for LC ranged from 0.5% (bladder) to 4.6% (hypopharynx); for 5-year OS 0.5% (bladder) to 8.7% (nasopharynx). For Australia, treatment of all cancers considered in this thesis translates into 16,177 lives saved in the next decade by use of appropriate evidence-based radiotherapy. 95 elements of uncertainty were considered in deterministic sensitivity analysis. The model was robust in sensitivity analysis. For 15 of 19 cancer types, the irreplaceable benefit of radiotherapy was similar to the baseline estimate.
Conclusions: Radiotherapy provides important and irreplaceable population-level benefits for cancer patients in Australia. The additional population benefit of CRT is small. This approach is now being used to determine other national and global estimates of radiotherapy benefit.