Estimates of cancer incidence, mortality and survival in aboriginal people from NSW, Australia

Stephen Morrell,Deborah Baker,Hui You

doi:10.1186/1471-2407-12-168

Abstract

BackgroundAboriginal status has been unreliably and incompletely recorded in health and vital registration data collections for the most populous areas of Australia, including NSW where 29% of Australian Aboriginal people reside. This paper reports an assessment of Aboriginal status recording in NSW cancer registrations and estimates incidence, mortality and survival from cancer in NSW Aboriginal people using multiple imputation of missing Aboriginal status in NSW Central Cancer Registry (CCR) records.MethodsLogistic regression modelling and multiple imputation were used to assign Aboriginal status to those records of cancer diagnosed from 1999 to 2008 with missing Aboriginality (affecting 12-18% of NSW cancers registered in this period). Estimates of incidence, mortality and survival from cancer in NSW Aboriginal people were compared with the NSW total population, as standardised incidence and mortality ratios, and with the non-Aboriginal population.ResultsFollowing imputation, 146 (12.2%) extra cancers in Aboriginal males and 140 (12.5%) in Aboriginal females were found for 1999-2007. Mean annual cancer incidence in NSW Aboriginal people was estimated to be 660 per 100,000 and 462 per 100,000, 9% and 6% higher than all NSW males and females respectively. Mean annual cancer mortality in NSW Aboriginal people was estimated to be 373 per 100,000 in males and 240 per 100,000 in females, 68% and 73% higher than for all NSW males and females respectively. Despite similar incidence of localised cancer, mortality from localised cancer in Aboriginal people is significantly higher than in non-Aboriginal people, as is mortality from cancers with regional, distant and unknown degree of spread at diagnosis. Cancer survival in Aboriginal people is significantly lower: 51% of males and 43% of females had died of the cancer by 5 years following diagnosis, compared to 36% and 33% of non-Aboriginal males and females respectively.ConclusionThe present study is the first to produce valid and reliable estimates of cancer incidence, survival and mortality in Australian Aboriginal people from NSW. Despite somewhat higher cancer incidence in Aboriginal than in non-Aboriginal people, substantially higher mortality and lower survival in Aboriginal people is only partly explained by more advanced cancer at diagnosis.

Highlights

Aboriginal status has been unreliably and incompletely recorded in health and vital registration data collections for the most populous areas of Australia, including NSW where 29% of Australian Aboriginal people reside
Model used in multiple imputation From the logistic regression model applied to cancer records with known Aboriginal status, most of the odds ratio estimates were statistically significant (Table 1)
Despite some uncertainties around the extent of cancer incidence in NSW Aboriginal people, it is certain that NSW Aboriginal people suffer an unacceptable excess of preventable cancers, of the lung, digestive tract and female genital tract

Summary

Introduction

Aboriginal status has been unreliably and incompletely recorded in health and vital registration data collections for the most populous areas of Australia, including NSW where 29% of Australian Aboriginal people reside. Aboriginality has been unreliably and incompletely recorded in health and vital registration data collections for the most populous areas of Australia, including NSW, the most heavily populated state where one third of the Australian population and 29% of Australia’s Aboriginal people reside [1]. Australian Aboriginal people suffer disproportionately higher morbidity and mortality than the non-Aboriginal population [2]. Cancer mortality for Aboriginal people in NSW has been estimated previously for 1994-2002 [3], and was found to be significantly higher than for NSW overall, by 71% in males and by 65% in females. Colorectal and stomach cancer in both sexes, oesophageal cancer in males, and cervical, pancreatic and kidney cancer in females, were the main cancers responsible for the overall cancer mortality excess in NSW

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