A study on microsatellite instability status for colorectal serrated lesions / 中华内科杂志

ABSTRACT

Objective To verify the traditional serrated pathway by comparing microsatellite instability(MSI) status among traditional serrated adenoma, traditional adenoma, serrated colorectal cancer and non-serrated coloreetal cancer. Methods Seventy-five paraffin-embedded tissue samples, including 15 with serrated adeneearcinoma (Sca), 20 with non-serrated adenocareinoma (N-Sca), 20 with traditional serrated adenoma(TSA) and 20 with villous adenoma(AD) were collected from the pathology department of our hospital. Genomic DNA was extracted from these samples and then amplified with fluorescently-labeled primer specific for BAT25 and BAT26. The MSI status was detected with DNA automatic sequencer. Results Six of 18 samples with TSA harbored MSI-H and twelve MSI-L/MSS; 18 samples with conventional adenoma were exclusively of MSS; 3 of 13 samples of serrated carcinoma harbored MSI-H and ten MSI-L/MSS; 18 of 19 N-Sca samples harbored MSI-L/MSS and only one MSI-H. With Chi-square test, the MSI frequency in AD group and N-Sca group was significantly lower than that in TSA group and Sca group ( P < 0. 05 ) ; but with no statistical difference between the TSA group and Sca groups ( P > 0. 05 ). Conclusion MSI-H frequency in AD group and N-Sca group was obviously lower than that of TSA group and Sca group. It is concluded that there might be a new traditional serrated neoplasia pathway which is different from the conventional adenoma-carcinoma carcinogenesis pathway, but we still need prospective follow-up studies to verify its existence.