Relationships of obesity and diabetes mellitus to other primary cancers in surgically treated gastric cancer patients

BackgroundOther primary cancers (OPC) have been reported in gastric cancer (GC) patients. Recent studies have shown relationships of obesity and diabetes mellitus to cancer development in several organs. The purpose of this study was to investigate the relationships of obesity and diabetes mellitus (DM) to the prevalence of OPC in GC patients.MethodsWe reviewed 435 GC patients who were treated surgically and followed their outcomes after surgery. Patients with body mass index (BMI) ≥ 25 kg/m2 were defined as obese. Fasting plasma glucose (FPG) and HbA1c levels were examined before surgery.ResultsOPC was observed in 109 GC patients (25.1%): 40 (9.2%) with synchronous OPC and 76 (18.2%) with metachronous OPC. The most common OPC was colorectal cancer (22.8%). OPC was frequently observed in patients with DM (p = 0.0022), and DM was an independent risk factor for the occurrence of OPC (odds ratio, 2.215; 95% confidence interval, 1.2007–4.0850; p = 0.011). Synchronous OPC was frequently observed in patients with obesity (p = 0.025), and obesity was an independent risk factor for the occurrence of synchronous OPC (odds ratio, 2.354; 95% confidence interval, 1.1246–4.9279; p = 0.023). Metachronous OPC was frequently observed in patients with DM (p = 0.0071), and DM was an independent risk factor for the occurrence of OPC (odds ratio, 2.680; 95% confidence interval, 1.0291–6.9780; p = 0.044).ConclusionThere is a need to be aware of the possibility of OPC in GC patients with DM/obesity. They should undergo intensive screening for OPC before and after gastrectomy.