Background: Early prevention and diagnosis are key to reducing the huge burden of gastric cancer (GC). Nearly half of the population worldwide are suffering from some form of digestive tract conditions (symptoms/diagnoses, DTCs) but their relations with GC are not well understood. We aim to explore the relationships (especially dose–effect relationships) between GC and DTCs.
Methods: This study used data from a community-based case–control study in Anhui, China during 2016– 2019 and performed multivariate conditional logistic regression modeling of the associations between GC and DTCs.
Results: A total of 2255 participants (451 cases and 1804 controls) completed the study. Statistically significant relations (P< 0.05) were found between GC and the presence of gastroesophageal reflux [odds ratio (OR)=1.41], odynophagia (OR=1.87), stomach discomfort (OR=1.86), poor appetite (OR=2.01) and Helicobacter pylori  (H. pylori ) infection (OR=4.39). When the DTCs were divided into duration grades, all these ORs presented an increasing trend (P< 0.05), being 1.89 to 2.45 for gastroesophageal reflux, 1.63 to 3.78 for stomach discomfort, 2.36 to 5.29 for poor appetite, and 3.95 to 10.03 for H. pylori  infection. When the DTCs were divided into severity grades, the ORs also witnessed an increasing trend (P< 0.05), being 1.69 to 2.52 for gastroesophageal reflux, 2.44 to 3.56 for stomach discomfort, and 2.22 to 2.75 for poor appetite. When the DTCs were divided into duration-severity grades, the ORs displayed a much steeper increasing trend, being 0.49 to 4.96 for gastroesophageal reflux, 1.50 to 6.33 for odynophagia, 0.47 to 3.32 for stomach discomfort, and 0.40 to 10.47 for poor appetite. In contrast, the ORs for the lower DTCs were generally tested without statistical significance.
Conclusion: The study revealed consistent dose–effect associations between GC and duration of gastroesophageal reflux, stomach discomfort, poor appetite, and H. pylori  infection; severity of gastroesophageal reflux, stomach discomfort and poor appetite; and duration-severity of gastroesophageal reflux, odynophagia, stomach discomfort and poor appetite. These should inform future prevention, diagnosis and further research in patients with GC.
Keywords: gastric cancer, digestive tract, symptoms, case–control study, dose–effect relations