Comprehensive allelotype study of ovarian tumors of low malignant potential: Potential differences in pathways between tumors with and without genetic predisposition to invasive carcinoma

Ovarian tumors of low malignant potential (LMP) are intermediate between ad enomas and ovarian carcinomas (OC); however, the relevance of LMP to ovaria n carcinogenesis is not clear. We performed a comparative analysis of allel otypes in 50 cases of LMP (42 mucinous and 8 serous) and 23 cases of OC (15 mucinous and 8 serous) to investigate any differences in genetic changes. Analysis of loss of heterozygosity (LOH) using 25 microsatellite markers re portedly associated with OC revealed that the total LOH frequency at each m arker was significantly lower in LMP than in OC (p < 0.01). However, 9 (36% .) loci showed higher LOH frequency in mucinous LMP than in mucinous OC. A genome-wide scan for LOH using 91 microsatellite markers and fine mapping r evealed that LOH at D7S1805 (7q35) is characteristic of mucinous LMP (19.4% in mucinous LMP, 8.3% in mucinous OC). We further studied LOH in 3 cases o f mucinous OC that were accompanied by mucinous LMP lesions. In 2 cases, LO H frequency was higher in the carcinoma portion than in the morphologically LMP portion. The other case showed microsatellite instability in the morph ologically LMP portion and LOH in the carcinoma portion. Our results sugges t the presence of an LMP-to-OC developmental sequence and the existence of a subset of LMP that does not develop into OC in the mucinous subtype of ov arian tumors. (C) 2001 Wiley-Liss, Inc.