Lung Cancer Characteristics and Survival Among Smokers, Former Smokers, and Never Smokers Within an Australian Lung Cancer Registry.

Abstract

Introduction: Cigarette smoking is a major risk factor for lung cancer. Lung cancer in never smokers differs from lung cancer in smokers, with higher female prevalence, earlier onset, and greater proportion of adenocarcinoma, and increased chance of an associated genetic predisposition. This study aimed to explore differences in patient, disease and management factors between smokers, former smokers, and never smokers diagnosed with primary lung cancer, using an Australian registry-based dataset to describe real world lung cancer survival outcomes. Method(s): This retrospective cohort evaluated consecutively diagnoses registered into the Victorian Lung Cancer Registry in Australia from July 2011 to September 2024. De- mographics, clinical outcomes and overall survival analyses were stratified smoking status defined as never, ex and current smokers. Result(s): This study included 2,451 never smokers (12.8%), 9,954 ex-smokers (51.8%) and 6,799 current smokers (35.4%). Current smokers were younger at diagnosis (68 years IQR 60-75), never smokers 70 (IQR 61-79) and ex-smokers 73 (IQR 67-80). Never smokers were more likely female (70% vs 44% overall), less likely of Indigenous status (0.1% vs 1.0% overall) and more likely from a higher socioeconomic background (61% vs 47%). Never smokers had a ECOG performance score of 0 (47% vs 33% overall), and with no comorbidities (62% vs 44% overall). Median survival for NSCLC never smokers (n=15,292) was 3.3 years (95% CI 2.9-3.7), ex-smokers 1.7 years (HR 1.48 (1.39-1.58), p<0.001) and current smokers 1.4 years (HR 1.63 (1.52-1.75), p<0.001), Figure 1. Median survival for SCLC (n=2,045) never smokers was 1.2 years (95% CI 0.94-2.3), exsmokers 0.73 years (HR 1.62 (1.16-2.28), p=0.005), and current smokers 0.78 years (HR 1.46 (1.04-2.05), p=0.027) Figure 2. Conclusion(s): Smoking status affected the real world lung cancer survival outcomes in our Australian cancer registry. This highlights the importance of clearly defining and collecting smoking history in addition to smoking cessation strategies.