Frequent Microsateffite Instability in Epithelial Borderline Ovarian Tumors'

To further define the genetic events that could lead to the development ofborderline ovarian tumors (BOTs), we analyzed 13 microsateffite mark era on chromosomes 3p and q in 18 BOTs and compared the results to 31 serous invasive epithelial ovarian cancers (IEOCs). Five of the 18 BOTs showed microsateilite instability (MSI) at one or more loci, compared to only 2 ofthe 31 IEOCs StUdied(P < 0.04). In two of these five BOTs, MSI was found in multiple loci. All BOTs with MSI were serous, while none of the mucinous type showed any alteration. Loss of heterozygosity was found in only 1 ofthe 18 BOTs, but in 12 ofthe 31 IEOCs (P < 0.01). This first report of a relatively high percentage of MSI in BOTs opens a wide spectrum of new hypotheses for borderline ovarian tumorigenesis as well as several new research avenues.