Evaluating prognostic factors for sex differences in lung cancer survival: A retrospective analysis of real-world data in Australia

Abstract Background Lung cancer survival rates are higher among women than men across many populations globally. We examined real-world data on prognostic factors for lung cancer in Australia and assessed their contribution to the sex survival disparity. Methods This was a retrospective analysis of data from the Victorian Lung Cancer Registry. People diagnosed with lung cancer during 2016-2022 were included with follow-up to August 2023. One-year overall survival was estimated by sex and stratified by four domain prognostic factors. The contribution of four domains of factors (patients' characteristics, smoking history, tumour-related and treatment-related factors) to sex-based survival differences (alone and jointly) was assessed with multiple Cox proportional hazard regressions. Results A total of 5,313 women and 6,540 men were diagnosed with lung cancer, with median 1-year survival 76.5% and 69.4%, respectively. The unadjusted hazard of all-cause death was significantly higher for men than women 1-year post-diagnosis (HR = 1.38, 99% CI: 1.28–1.49, p<0.0001). The survival disparity remained statistically significant when each domain of prognostic factors was evaluated individually. Multivariable analysis revealed that treatment-related factors explained about 77% of the overall survival difference, followed by smoking history and tumour-related factors (explaining 26% and 24% respectively). After adjusting for all four domains of prognostic factors together, the excess risk of death among men was reduced by about 82% (HR=1.05, 99% CI: 1.00-1.11, p=0.02). Conclusion The sex-related lung cancer survival disparity in Australia is largely accounted for by treatment disparities, indicating an opportunity to explore sex differences in treatment preferences, options, and access. Micro Abstract We analysed real-world data from a population-based lung cancer registry in Australia to examine prognostic factors and their contribution to sex-related survival disparities. In this retrospective cohort study of 11,853 patients with lung cancer, we assessed four domains of prognostic factors—patient characteristics, smoking history, tumor-related factors, and treatment-related factors—to determine their impact on differences in survival between men and women.