Leisure-time physical activity and gastric cancer risk: a pooled study within the StoP project

BACKGROUND: Although physical activity (PA) has been recognized as a favourable factor in the prevention of various diseases, including certain forms of cancer, the relationship between PA and gastric cancer (GC) is not yet fully comprehended. For this reason, this study aims provide data from a pooled analysis of case-control studies within the Stomach cancer Pooling (StoP) Project to estimate the association between leisure-time PA and the occurrence of GC. METHODS: Six case-control studies from StoP project collected data on leisure-time PA, for a total of 2,343 cases and 8,614 controls. Subjects were classified into three leisure-time PA categories, either none/low, intermediate or high, based on study-specific tertiles. We used a two-stage approach. Firstly, we applied multivariable logistic regression models to obtain study-specific odds ratios (ORs) and corresponding 95% confidence intervals (CIs) then, we used a random-effect models to obtain pooled effect estimates. Heterogeneity was assessed using Q and I2 statistics. We performed stratified analyses according to demographic, lifestyle and clinical covariates. RESULTS: The meta-analysis showed ORs of GC with no significant differences between intermediate vs low and high vs low PA level (OR 1.05 [95%CI 0.76-1.45]; OR 1.23 [95%CI 0.78-1.94], respectively). GC risk estimates did not strongly differ across strata of selected covariates except for age ≤ 55 years old (high vs low level: OR 0.72 [95%CI 0.55-0.94]). CONCLUSIONS: An association between leisure time PA and GC, apart from some suggestion of decreased risk below age 55, was not found. This may reflect specific characteristics of GC at younger age, or the presence of a cohort effect mediating and interacting with socioeconomic determinants of GC. KEY MESSAGES: • An association between leisure time PA and GC, apart from some suggestion of decreased risk below age 55, was not found. • GC risk estimates did not strongly differ across strata of selected covariates except for age ≤ 55 years old.