Cancer survival disparities worsening by socio-economic disadvantage over the last 3 decades in new South Wales, Australia

Hanna E. Tervonen, Sanchia Aranda, David Roder, Hui You, Richard Walton, Stephen Morrell, Deborah Baker, David C. Currow

Public concerns are commonly expressed about widening health gaps. This cohort study examines variations and trends in cancer survival by socio-economic disadvantage, geographical remoteness and country of birth in an Australian population over a 30-year period. Data for cases diagnosed in New South Wales (NSW) in 1980-2008 (n = 651,245) were extracted from the population-based NSW Cancer Registry. Competing risk regression models, using the Fine & Gray method, were used for comparative analyses to estimate sub-hazard ratios (SHR) with 95% confidence intervals (CI) among people diagnosed with cancer. Increased 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/remote areas compared with major cities (SHR 1.05, 95% CI 1.03-1.06). People born outside Australia had a similar or lower risk of cancer death than Australian-born (SHR 0.99, 95% CI 0.98-1.01 and SHR 0.91, 95% CI 0.90-0.92 for people born in other English and non-English speaking countries, respectively). An increasing comparative risk of cancer death was observed over time when comparing the most with the least socio-economically 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; p < 0.001 for interaction between disadvantage quintile and year of diagnosis). There is a widening gap in comparative risk of cancer death by level of socio-economic disadvantage that warrants a policy response and further examination of reasons behind these disparities.