Data sources and statistical analyses
Mortality-to-incidence ratios
Age-standardized all-cancer incidence and mortality rates for each health region were obtained from Statistics Canada (\cite{upbzrh},\cite{srikt}), and is available in three-year aggregates. We used the most recently available data (2010-2012) for all provinces and territories, with the exception of Quebec, for which the most recently available incidence data is from 2008-2010. Incidence and mortality rates were age-standardized using the 2011 Canadian Census population structure. All-cancer age-standardized mortality-to-incidence ratios (MIRs) were then calculated for each health region as the age-standardized mortality rate divided by the age-standardized incidence rate.
Distance to radiotherapy center
In order to calculate each health region's distance to nearest radiotherapy center, we first obtained a list of radiotherapy centers in Canada from The Directory of Radiotherapy Centres (DIRAC). DIRAC is an online international registry of radiotherapy centers maintained by the International Atomic Energy Agency (IAEA), and is estimated to include 90% of existing radiotherapy facilities worldwide. It is updated daily with information provided to the IAEA by radiotherapy centers or national organisations. Equipment and centers that are no longer operational are not deleted from the database, but are recorded as non-operational. For this study, we filtered the database to include only radiotherapy centers and equipment that were operational in 2012, to most closely match the time period for our incidence and mortality data.
All health regions were then mapped using GIS software (QGIS v. XX), using 2015 boundary files from Statistics Canada (XX), and the centroid of each health region polygon was auto-calculated. The Euclidean (straight-line) distance, in kilometers, from each health region centroid to the nearest radiotherapy center was measured, irrespective of provincial boundaries.