Purpose: Australian Aboriginal and Torres Strait Islander diagnosed with cancer are known to experience poorer survival, with these survival disparities mainly restricted to the first 2 years after diagnosis. With improved accuracy and completeness of identifying Aboriginal and Torres Strait Islander peoples over the whole study period, our goal was to examine whether the survival disparity among Aboriginal and Torres Strait Islander peoples diagnosed with cancer in Queensland has changed over time.

Methods: Population-based data from the Queensland Cancer Register between 1998 and 2017 for Queenslanders aged 15 years and over at diagnosis (n = 377,963; 1.6% Aboriginal and/or Torres Strait Islander) were used to determine whether this disparity has reduced over time. Flexible parametric survival models incorporating time-varying coefficients were used to examine the association between Aboriginal and Torres Strait Islander status and cancer-specific survival within 5 years of diagnosis.

Results: The adjusted 5-year cancer-specific survival rate for Aboriginal and Torres Strait Islander people diagnosed with cancer increased from 60.5% (95% CI 59.2-61.9%) in 1998-2007 to 65.5% (95% CI 64.3-66.6%) in 2008-2017, with the corresponding estimates for other Queenslanders being 66.6% (95% CI 66.4-66.8%) and 70.1% (95% CI 69.9-70.3%). The survival disparity was significant only for the first 3 years since diagnosis for 1998-2007; however, it was significantly (p ≤ 0.02) elevated for all five time intervals for 2008-2017, with similar average hazard ratios (95% CIs) over the 5-year interval after diagnosis of 1.45 (1.36-1.55) for 1998-2007 and 1.42 (1.34-1.50) for 2008-2017.

Conclusion: Although survival has increased over time, the lack of improvement in the disparity in cancer survival experienced by Aboriginal and Torres Strait Islander cancer patients highlights the urgent need to better understand the multifaceted and completed factors that underlie this gap to guide targeted, evidence-based interventions and support their implementation across the health sector.