Exploring differences in survival from cancer among indigenous and non-indigenous Australians: Implications for health service delivery and research

Abstract

The aim of this study is to compare cancer survivals of Indigenous and non-Indigenous Australians and consider health-service and research implications Cancer registry data from South Australia were used to calculate disease-specific survivals for Indigenous (n=671) and sampled non-Indigenous (n=15,799) patients diagnosed during 1977-2007, using Kaplan-Meier estimates and Cox proportional hazards regression. Indigenous and non-Indigenous five-year survivals were respectively: 40% and 57% for all cancer sites combined; 61% and 80% for female breast; 34% and 56% for colon/rectum; and 63% and 73% for cervix; whereas one-year survivals for cancers of unknown primary site were 5% and 22% respectively. Conversely, although not statistically significant (p=0.262), lung cancer survival tended to be higher in Indigenous than non-Indigenous patients. For all sites combined, Indigenous patients had lower survivals up to 70-79 years. The relative risk of death in Indigenous compared with non-Indigenous patients was 2.0 after adjusting for socio-demographic factors and diagnostic period, reducing to 1.4 when also adjusting for prognosis by primary site. Relative risks were 3.7 and 2.7 respectively for Indigenous compared with non-Indigenous patients from Far North remote communities. We conclude that relative risks for Indigenous compared with non-Indigenous patients for all cancers combined are elevated, as seen in the Northern Territory and Queensland. Despite uncertain accuracy of recording of Indigenous status, independent studies show risk elevations and point to the need to prevent cancers, particularly those of high lethal potential, to detect cancers earlier, and to complete planned treatment. A concerted health-service response is needed to address contributing geographic, socio-economic and cultural factors.