Pathologic Characteristics of Colorectal Cancers with DNA Replication Errors

Unstable microsatellite repeat sequences or DNA replication errors(RER) due to defective mismatch repair genes have been reported in a subset of sporadic colorectal tumors and in most tumors of patients of hereditary nonpolyposis colorectal carcinoma(HNPCC). To elucidate the clinicopathological correlation of these RER-positive cancers, we examined 16 cases of colorectal carcinoma of different histologic subtypes(6 cases of carcinoma with no gland formation, 5 cases of mucinous carcinoma and 5 cases of gland forming carcinoma). We detected RER .in five cases. The patients with RER-positive cancers had a marked preponderance of carcinoma with no gland formation(4 out of 6 carcinomas with no gland formation were RER-positive cancers) and of cancers proximal to splenic flexure(all of the RER-positive cases were proximal colon carcinomas). We conclude that RER-positive cancers have unique pathologic features that may be useful for the screening and counselling of patients with hereditary colon cancers.ope