Individual and joint associations of socioeconomic inequalities and unhealthy lifestyle with incident gastric cancer: A prospective cohort study.

[OBJECTIVES] Gastric cancer (GC) remains a significant public health challenge, with accumulating evidence indicating an association between socioeconomic status (SES) and GC risk. This study aimed to examine the independent and synergistic effects of SES and lifestyle on GC incidence within a large prospective cohort.

[STUDY DESIGN] Prospective cohort study.

[METHODS] Data were analysed from 349,908 UK Biobank participants using latent class analysis to determine SES (household income, education, employment). Lifestyle was assessed based on smoking status, alcohol consumption, physical activity, body mass index and diet. Multivariable Cox regression tested associations between SES, lifestyle and GC, with mediation and interaction analyses used to explore their relationships.

[RESULTS] SES was significantly associated with GC risk (hazard ratio [HR] = 1.35, 95 % confidence interval [CI], 1.20-1.52). An unhealthy lifestyle was also linked to increased GC risk (HR = 1.48, 95 % CI, 1.30-1.68). Individuals with low SES and an unhealthy lifestyle had a 195 % higher risk of GC compared to those with high SES and a healthy lifestyle (HR = 2.95, 95 % CI, 2.11-4.11). Mediation analysis indicated that 5.26 % of the SES-GC risk association was mediated by lifestyle factors. No significant interaction between SES and lifestyle was observed.

[CONCLUSIONS] Low SES was related to an increased risk of GC, some of which may be mediated by unhealthy lifestyle. Public health initiatives should focus on addressing socioeconomic disparities and improving lifestyle factors to reduce GC incidence.