RESUMEN
Objective To study microsatellite instability(MSI) in multiple primary colorectal carcinoma(MPCC) and solitary colorectal tumor(SCT), and to explore the relationship between the expression of mismatch repair(MMR)、p53、Bax、PCNA and MSI. Methods The expression of MMR、p53、Bax、 PCNAwere detected by immunohistochemical staining, and MSI at five microsatellite loci were examined by PCR-SSLP in 51 tumors from 38 MPCC patients and 35 SCT cases. Results The replication errors positive phenotype was observed in 27 of 51(53%) tumor foci from MPCC cases, and in 6 of 35(17%) SCT cases. There was an inverse correlation between replication errors (RER) positive and expression of p53; the PCNA labeling index of RER positive tumors were significantly lower than of RER negative tumors; RER positive related strongly with poor differentiation, the proclivity for proximal colon. Conclusions MSI may play an important role in the development of MPCC and may be used as a tumor marker of MPCC.