Objective: To evaluate the frequency of MSI in epithelial ovarian tumors and its relationship with clinicopathologic features. Methods: Ninety fresh specimens of epithelial ovarian tumors, including 74 primary and 16 secondary tumors, were collected. Microsatellite analysis was carried out using 5 mono- and dinucleotide markers from the National Cancer Institute Consensus Panel by fluorescence-labeled polymerase chain reaction. Results: Of 90 epithelial ovarian tumors analyzed, 18 demonstrated a high level of microsatellite instability (MSI-H), 30 demonstrated a low level of microsatellite instability (MSI-L), and the remaining 42 exhibited microsatellite stability (MSS). Frequency of microsatellite instability (MSI) at loci BAT-25 was higher than that at any other loci. No correlation was found between MSI level and patient age, tumor type, tumor differentiation (P>0.05). But the microsatellite instability-high phenotype correlates with clinical stage.It tended to occur more frequently in early-stage tumors (P=0.03). Conclusion: The frequent MSI in epithelial ovarian tumors suggests that it is an early event to involve in the development of epithelial ovarian tumors.
