FREQUENT MICROSATELLITE INSTABILITY IN EPITHELIAL BORDERLINE OVARIAN-TUMORS

To further define the genetic events that could lead to the developmen t of borderline ovarian tumors (BOTs), we analyzed 13 microsatellite m arkers 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 microsatellite instability (MSI) at one or more loci, comp ared to only 2 of the 31 IEOCs studied (P < 0.04), In two of these fiv e BOTs, MSI was found in multiple loci, All BOTs with MSI were serous, while none of the mucinous type showed any alteration, Loss of hetero zygosity was found in only 1 of the 18 BOTs, but in 12 of the 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.