Descriptive analysis of screen-detected versus clinically diagnosed lung cancer cases: evidence of earlier stage...

Lung cancer is the leading cause of cancer-related deaths worldwide, largely due to late-stage diagnosis. Lung cancer screening by computed tomography (CT) reduces mortality by detecting cancers earlier in high-risk individuals, prompting Australia to launch the National Lung Cancer Screening Program (NLCSP) in 2025. Understanding the differences between screen-detected and clinically diagnosed lung cancers is essential for evaluating the impact of screening.

To compare demographic, clinical and treatment characteristics of screen-detected versus clinically diagnosed lung cancer cases in Australia and assess evidence of earlier stage shift and treatment differences.

Screen-detected cases were sourced from the Queensland Lung Cancer Screening Study (QLCSS) and International Lung Screening Trial (ILST), including cancers identified at baseline CT and up to 5 years of follow-up. Clinically diagnosed cases from the corresponding periods were identified through Queensland Oncology Online. Data included demographics, smoking history, comorbidities, cancer stage and treatments. Wilcoxon rank-sum, Fisher exact and chi-squared tests (P < 0.05) were used to compare the groups. Sensitivity analyses included 1:2 case-control and NLCSP-eligible subgroup analysis.

Screen-detected cases were more likely to be diagnosed at stage I (63% vs 28%, P_adj < 0.01) and underwent surgery (P_adj < 0.05), whereas clinically detected cases were mostly stage IV (36% vs 14%) and received more radiotherapy (P_adj < 0.001). These differences persisted in sensitivity and subgroup analyses.

Screen-detected lung cancers show a stage shift towards earlier diagnosis and higher surgical treatment rates, supporting the potential effectiveness of the NLCSP.