Endoscopic and clinicopathologic characteristics of early gastric cancer with high microsatellite instability

AIM： To investigate endoscopic and clinicopathologic characteristics of early gastric cancer （EGC） according to microsatellite instability phenotype. METHODS： Data were retrospectively collected from a single tertiary referral center. Of 981 EGC patients surgically treated between December 2003 and October 2007, 73 consecutive EGC patients with two or more microsatellite instability （MSI） mutation [high MSI （MSI-H）] and 146 consecutive EGC patients with one or no MSI mutation （non-MSI-H） were selected. The endoscopic and clinicopathologic features were compared between the MSI-H and non-MSI-H EGC groups.RESULTS： In terms of endoscopic characteristics, MSI-H EGCs more frequently presented with elevated pattern （OR 4.38, 95% Cl： 2.40-8.01, P 〈 0.001）, moderate- to-severe atrophy in the surrounding mucosa （OR 1.91, 95% CI： 1.05-3.47, P = 0.033）, antral location （OR 3.99, 95% CI： 2.12-7.52, P 〈 0.001） and synchronous le- sions, compared to non-MSI-H EGCs （OR 2.65, 95% CI： 1.16-6.07, P = 0.021）. Other significant clinicopatholog- ic characteristics of MSI-H EGC included predominance of female sex （OR 2.77, 95% CI： 1.53-4.99, P 〈 0.001）, older age （〉 70 years） （OR 3.30, 95% CI： 1.57-6.92, P = 0.002）, better histologic differentiation （OR 2.35, 95% Cl： 1.27-4.34, P = 0.007）, intestinal type by Lau- ren classification （OR 2.34, 95% CI： 1.15-4.76, P = 0.019）, absence of a signet ring cell component （OR 2.44, 95% CI： 1.02-5.86, P = 0.046）, presence of mu- cinous component （OR 5.06, 95% Cl： 1.27-20.17, P = 0.022）, moderate-to-severe lymphoid stromal reaction （OR 3.95, 95% CI： 1.59-9.80, P = 0.003）, and co-exist- ing underlying adenoma （OR 2.66, 95% CI： 1.43-4.95, P = 0.002）. CONCLUSION： MSI-H EGC is associated with unique endoscopic and clinicopathologic characteristics includ- ing frequent presentation in protruded type, co-exist- ing underlying adenoma, and synchronous lesions.