Clinicopathologic characteristics of replication error-positive gastric carcinoma

Microsatellite instability (MI), an expansion or contraction of microsatellites, is a manifestation of replication errors (RERs) that is recognized as performing an important role in carcinogenesis in a proportion of gastric carcinomas. We analyzed 96 cases of sporadic gastric carcinomas for the occurrence of MI in BAT-26 and other six microsatellite loci. Gastric carcinomas with BAT-26 alteration demonstrated a higher proportion of unstable loci in other examined microsatellites than did gastric carcinomas without BAT-26 alteration. We classified gastric carcinomas with BAT-26 alteration as RER+ and compared the RER status with their clinicopathologic features. Ten (10.4%) of 96 gastric carcinomas showed RERs: 2 (7.7%) of 26 early gastric carcinomas and 8 (11.4%) of 70 advanced gastric carcinomas were RER+. RER+ gastric carcinomas were significantly associated with older age, elevated gross type (Borrmann Type 2 or EGC IIa), expanding growth pattern (Ming's classification), and minimal desmoplasia. Although statistically not significant, RER+ gastric carcinomas showed more frequent intestinal type (Lauren's classification), more antral involvement, and lower lymph node metastasis than did RER- gastric carcinomas. There was no association between RER status and intratumoral lymphocyte infiltration or histologic differentiation. In conclusion, RER+ gastric carcinomas demonstrated distinct clinicopathologic features, and BAT-26 was a useful marker for assessing the RER status of gastric carcinomas.