Cancer Survival Disparities In New South Wales, Australia Over 30 Years

Hanna TERVONEN, University of South Australia, Australia
ARANDA S. 2 , RODER D. 1,3 , YOU H. 3 , WALTON R. 3 , MORRELL S. 3 , BAKER D. 3 , CURROW D. 3

1 School of Health Sciences, Centre for Population Health Research, University of South Australia, Adelaide, Australia
2 Cancer Council Australia, Sydney, Australia
3 Cancer Institute NSW, Sydney, Australia

Purpose: Public concerns are commonly expressed about widening health gaps due to social inequities. This study examines variations and trends in cancer survival by geographical remoteness, socio-economic disadvantage and country of birth in an Australian population over a 30-year period.
Methods: Cancer diagnoses from the largest Australian state, New South Wales (NSW), for 1980-2008, were extracted from the population-based NSW Cancer Registry (n=651,245). Remoteness was measured using the Accessibility/Remoteness Index of Australia. Socio-economic disadvantage was measured using the Index of Relative Socio-Economic Disadvantage, based on data for Census Collection Districts (approximately 200-300 dwellings), and categorised into equal-population quintiles. Country of birth was categorised as Australia, other English speaking, non-English speaking, and unknown. Competing risk regression models, using the Fine & Gray method, were used to compute sub-hazard ratios (SHRs) with 95% confidence intervals (CIs) for comparative analyses.
Results: After adjusting for sex, age, diagnostic period, cancer site, degree of spread (summary stage) and other study variables, a higher risk of cancer death was associated with living in the most socio-economically disadvantaged areas compared with the least disadvantaged areas (SHR 1.15, 95%CI 1.13-1.17), and in outer regional areas compared with major cities (SHR 1.05, 95%CI 1.03-1.06). People born in other English speaking countries had a similar risk (SHR 0.99, 95%CI 0.98-1.01) and those born in non-English speaking countries had a lower risk of cancer death (SHR 0.91, 95%CI 0.90-0.92) than the Australian-born. SHRs for cancer mortality were observed to increase over time by socio-economic disadvantage (comparing the most with the least disadvantaged areas): SHR 1.07 (95%CI 1.04-1.10) for 1980-1989; SHR 1.14 (95%CI 1.12-1.17) for 1990-1999; and SHR 1.24 (95%CI 1.21-1.27) for 2000-2008.
Conclusions: The contributions of co-morbidity and treatment access and practices need investigation to explain the cancer survival disparities detected in NSW.
Funding source: The NHMRC Program Grant (no. 0631946).