Distribution of Microsatellite Instability in Danish Ovarian Tumor Patients and the Prognostic Value in Ovarian Cancer Patients

Abstract

The repeated frequency of microsatellite instability (MSI) in ovarian cancer (OC) ranges from 0% to 50%. Most MSI studies including OC patients have involved relatively small number of tumors, a wide range of different MSI markers, different patient characteristics, and varying criteria for defining tumors as MSI positive. Thus, no conclusive evidence about MSI occurrence in OC has been provided and the large variation has made interpretation of these previous studies difficult. The majority of MSI studies have been performed on OC cases with few borderline ovarian tumor (BOT) cases included. Few BOT studies showed no evidence of MSI, but in one study the frequency of MSI was 27.7% with all tumors of serous type, suggesting that MSI may play a role in the development of serous BOT. The aim of our study was to determine the frequency of MSI using a panel of 16 dinucleotide markers: TP53, D17S250, CACNLB1, D18S58, D19S49, DXS538, DXS454, D5S117, D5S107, D6S284, D6S305, D9S171, D9S15, D11S554, D11S29, and D13S272 in tissue from patients with OC or BOT and to correlate the presence of MSI at these markers with the clinical information, such as FIGO stage, histological type, age, and survival in OC. The overall frequencies of MSI were within 2-10%. We observed MSI at different loci and with different extent (2.3-9.8%) in the different histopathological types. In both BOT and OC cases, we observed that all high MSI (MSI-H) were of serous type. No significant difference in disease specific survival was found between stage III/IV OC patients who presented MSI compared to patients being microsatellite stable (MSS) (p = 0.72). In conclusion, we found no association to any of the clinical parameters evaluated, although a tendency of a higher frequency of MSI was observed among serous OC.