Role of preoperative colonoscopy in patients with gastric cancer: A case control study of the prevalence of coexisting colorectal neoplasms

Background: We evaluated the prevalence of coexisting asymptomatic colorectal neoplasm (CRN) in patients with gastric cancer (GC). Methods: Preoperative colonoscopic examinations were performed in 495 patients with GC who underwent gastrectomy between January 2009 and December 2010. To compare the prevalence of CRN in these patients with that in a normal population, we selected 495 sex- and age-matched persons who underwent colonoscopies for health screening. Risk factors for CRN were evaluated by univariate and multivariate analyses. Results: The overall incidence of CRN was 41.8 % (414/990). The prevalence of overall CRN, high-risk CRN, and colorectal carcinoma (CRC) were significantly higher in the GC group than in the control group (overall CRN: 48.9 % vs. 34.7 %; high-risk CRN: 28.3 % vs. 13.5 %; CRC: 2.6 % vs. 0.2 %; all P < 0.001). The presence of GC [odds ratio (OR), 1.82; 95 % confidence interval (CI), 1.4-2.38; P < 0.001], age ≥50 years (OR, 2.58; 95 % CI, 1.75-3.81; P < 0.001), and male sex (OR, 2.28; 95 % CI, 1.72-3.02; P < 0.001) were risk factors for overall CRN. In patients with GC, age ≥40 years (OR, 3.22; 95 % CI, 1.24-8.37; P = 0.016) and male sex (OR, 3.21; 95 % CI, 2.17-4.76; P < 0.001) were risk factors for overall CRN. Conclusions: The prevalence of coexisting CRN, including CRC, was higher in patients with GC than in the normal population. Preoperative colonoscopy is strongly indicated in patients with GC who are male and/or ≥40 years of age.