>23% of Aboriginals had significantly lower MIR (0.42 vs. 0.53, respectively; p < .0001) and shorter Euclidean distance to nearest radiotherapy centre (121km vs. 799km, respectively; p < .0001).
Findings: Health regions with a higher proportion of self-identified Aboriginals were significantly associated with higher all-cancer MIR in univariate analysis (r2 = 0.32, p < .0001). When stratified, health regions inhabited by ≤20% versus >20% of Aboriginals had significantly lower MIR (0.42 vs. 0.53, respectively; p < .0001) and shorter Euclidean distance to nearest radiotherapy centre (121km vs. 799km, respectively; p < .0001). However, in a recursive partitioning analysis examining both MIR and distance, health regions inhabited by >20% of Aboriginals had significantly higher MIR compared to those with ≤20%, irrespective of distance to nearest radiotherapy centre (p < .0001 for centres <121km; and p = .0001 for centres >121km). For health regions with ≤20% of Aboriginals, distance did not result in a significantly different MIR (p = 0.10).