Survival of Indigenous and non‐Indigenous Queenslanders after a diagnosis of lung cancer: a matched cohort study

Abstract

To compare survival of Indigenous and non-Indigenous lung cancer patients and to investigate any corresponding differences in stage, treatment and comorbidities. Cohort study of 158 Indigenous and 152 non-Indigenous patients (frequency-matched on age, sex and rurality) diagnosed with lung cancer between 1996 and 2002 and treated in Queensland public hospitals. Survival after diagnosis of lung cancer; effects of stage at diagnosis, treatment, comorbidities and histological subtype on lung cancer-specific survival. Survival of Indigenous lung cancer patients was significantly lower than that of non-Indigenous patients (median survival, 4.3 v 10.3 months; hazard ratio, 1.48; 95% CI, 1.14-1.92). Of 158 Indigenous patients, 72 (46%) received active treatment with chemotherapy, radiotherapy or surgery compared with 109 (72%) of the 152 non-Indigenous patients, and this treatment disparity remained after adjusting for histological subtype, stage at diagnosis, and comorbidities (adjusted risk ratio, 0.65; 95% CI, 0.53-0.73). The treatment disparity explained most of the survival deficit: the hazard ratio reduced to 1.10 (95% CI, 0.83-1.44) after inclusion of treatment variables in the proportional hazards survival model. The remaining survival deficit was explained by the higher prevalence of comorbidities among Indigenous cancer patients, mainly diabetes. Survival after a diagnosis of lung cancer is worse for Indigenous patients than for non-Indigenous patients, and differences in treatment between the two groups are mainly responsible.