Global distribution of lung cancer staging at diagnosis: a systematic review

Lung cancer remains the leading cause of cancer-related mortality worldwide, with stage at diagnosis significantly influencing survival outcomes. This systematic review evaluates global variations in lung cancer stage distribution at diagnosis and examines the associations of socioeconomic factors and screening programs with these disparities. We conducted a systematic review following PRISMA guidelines, searching PubMed, Embase, and grey literature up to August 14, 2024, to identify population- or hospital-based cancer registry data on lung cancer staging. Data from 36 countries were analyzed, focusing on the proportion of distant metastatic cases. We assessed associations with Human Development Index (HDI) and Socio-Demographic Index (SDI) using case-number-weighted linear regression model and evaluated time trends in countries with and without screening programs. Subgroup analyses explored variations by sex, age, and tumor type. Among the 35 countries analyzed in the main study, the median proportion of lung cancer cases diagnosed with distant metastasis was 50.8% (interquartile range: 44.8%–59.2%), ranging from 30.4% in Hungary to 81.3% in Brunei Darussalam. No significant associations were observed between HDI ( β = 2.274, P = 0.876) or SDI ( β = − 7.332, P = 0.420) and the proportion of lung cancer cases with distant metastases. In countries implementing screening programs, the proportion of metastatic cases has declined, e.g., in the United States (56.5% in 2004 to 48.5% in 2021) and England (54.7% in 2013 to 48.7% in 2021), with increased early-stage incidence in the United States and Republic of Korea. The proportion of patients in the metastatic stage is higher among males, younger patients, and those with small cell lung cancer. Significant global disparities in lung cancer stage at diagnosis highlight the critical role of screening programs in reducing metastatic cases. Enhancing early detection in resource-limited settings and standardizing registries are vital to improve outcomes and equity.