Improved cancer survival in the Northern Territory: identifying progress and disparities for Aboriginal peoples, 1991–2020

Objectives: To investigate cancer survival for Aboriginal and non-Aboriginal peoples in the Northern Territory during the period 1991–2020, across the 15 most prevalent primary cancer sites. 

Study design: Retrospective cohort study of Northern Territory Cancer Registry notifications. 

Setting, participants: NT residents diagnosed with an invasive cancer from 1 January 1991 to 31 December 2020. Main outcome measures: Five-year survival for all cancers and for 15 primary cancer sites by 10-year periods of diagnosis, and excess hazard ratios comparing excess mortality following cancer diagnosis for Aboriginal peoples compared with non-Aboriginal peoples. 

Results: Of 17 759 cancer registrations analysed, 3350 (18.9%) had Indigenous status recorded as Aboriginal. Five-year survival improved significantly from 1991–2000 to 2011–2020 for all populations, including Aboriginal (males, 20.5% to 37.1%; females, 32.3% to 47.2%) and non-Aboriginal (males, 50.0% to 65.9%; females, 64.5% to 75.4%). The gap in 5-year cancer survival for Aboriginal peoples closed by 12.4% (4.0 percentage difference) for females, but only by 2.4% (0.7 percentage difference) for males. For all 15 cancer sites, 5-year survival improved, but Aboriginal peoples experienced excess mortality, ranging from an excess hazard ratio of 1.3 for mortality following diagnosis of liver cancer to 6.1 for prostate cancer during the period 2011–2020. 

Conclusions: Cancer survival has improved for Aboriginal and non-Aboriginal peoples in the NT. However, the gap in survival outcomes for Aboriginal peoples persists. Further research is required on pathways to close the gap, including: improving access to care, understanding social and cultural factors, reducing diagnostic and treatment delays, and promoting greater equity of Aboriginal participation in clinical trials. Quality improvement approaches led by Aboriginal peoples should be prioritised to tailor culturally appropriate preventive strategies.