Diagnostic Interval and Social Determinants of Health in Lung Cancer: A Mixed-Methods Study in Chile

Background Lung cancer (LC) is the leading cause of cancer mortality worldwide and in Chile. Although Chile introduced an explicit guarantee (GES) of ≤60 days for diagnostic interval (DI: time between firsts consultation and diagnostic confirmation), evidence on how social determinants of health (SDH) shape this interval remains limited. Methods We conducted a convergent mixed-methods study with equal weighting (QUAL=QUAN). The quantitative strand was an analytical cross-sectional survey of adults with LC (n=80). The primary outcome was the DI, dichotomized at 60 days. Associations with SDH (gender, region, income quintile, education, health system) were assessed using bivariate tests and logistic regression. The qualitative strand comprised 37 semi-structured interviews (patients, caregivers, clinicians, civil society), thematically analyzed. Integration used a weaving narrative and joint displays to classify patterns as confirmation, expansion, or discordance. Results The reported DI was 30.5 days (mean 79.1; range up to 578). Quantitatively, income showed the clearest gradient: compared with the highest quintile, the second quintile had 5.79× higher odds of >60-day delay (p=0.049; 95%CI 1.011–33.21). Type of health system also suggested disadvantage in the public sector, with 57.1% versus 80.0% of private patients diagnosed within 60 days (OR for delay in public = 1.77; p=0.458). Differences by gender, region, and education were not statistically significant. Qualitative findings expanded these results by revealing the mechanisms underlying diagnostic delays: participants described fragmented pathways, centralization of specialists and technology in metropolitan areas, long-distance travel, test bottlenecks or malfunctions, frequent misdiagnoses (e.g., pneumonia), and health-literacy barriers in the public system and in regional areas. Taken together, the integrated analysis confirmed the quantitative trends for income and health system while expanding the understanding of geographic and educational influences, with no substantive discordances emerging across strands. Conclusions This is the first integration of social determinants of health and care trajectories in LC in Chile. Meeting a legal timeline between the first consultation to diagnostic confirmation interval < 60 days, does not ensure equity in diagnostic in Chile. Findings suggests the urgent need for stronger territory integration in oncology networks, decentralized diagnostic capacity, improved patient navigation, health-literacy education programs, and equity-stratified performance monitoring, including systematic SDH fields in cancer registries. These actions can shorten critical intervals, improve patient experience, and close access gaps in disadvantaged populations.