The Combined Effect of Dietary and Behavioral Risk Factors in Gastric Cancer: A Case-Control Study Using a Healthy...

Background/Objectives: Gastric cancer (GC) remains a major health challenge in high-incidence regions like Fujian Province, China. This study aimed to identify modifiable dietary and behavioral risk factors for GC and to evaluate their combined effect using a Healthy Lifestyle Index (HLI) in a high-incidence region of China. Methods: A case-control study was conducted at a tertiary hospital from June 2023 to December 2024, including 336 newly diagnosed GC cases and 336 healthy controls from Fujian Province. A Healthy Lifestyle Index (HLI, scored 0-10) was constructed from ten dietary and behavioral factors, with participants categorized into tertiles as healthy, moderate, or unhealthy. Results: The proportions of males and females were 56.5% and 43.5%, respectively. The mean age of the case group was 56.76 ± 10.83 years, significantly higher than that of the control group (53.86 ± 11.13 years, p < 0.001). The HLI incorporated ten behavioral/dietary components: sedentary behavior, smoking, alcohol consumption, tea drinking, physical activity, pickled and processed food intake, regular eating habits, fruit intake, vegetable intake, and red meat intake. Cases showed a higher proportion of unhealthy lifestyle patterns (34.8% vs. 26.8%), whereas controls showed a higher proportion of healthy lifestyle behaviors (41.7% vs. 37.5%); however, the overall between-group distribution of HLI categories was not statistically significant (p = 0.078). The multivariate logistic regression showed that the healthy group was associated with a lower risk of developing GC compared to the unhealthy group (aOR = 0.34, 95% CI: 0.20-0.57, p < 0.001). Conclusions: A healthier combined dietary and behavioral profile may be associated with lower odds of GC in this population. However, the observed associations should be interpreted cautiously because of the case-control design, the lack of H. pylori data, and the absence of formal validation of the HLI in the Fujian population. Prospective studies with objective dietary assessment and more detailed clinical characterization are warranted.