FREQUENT LOSS OF HETEROZYGOSITY ON CHROMOSOME-7 AND CHROMOSOME-9 IN BENIGN EPITHELIAL OVARIAN-TUMORS

It is presently unclear if ovarian cancers arise through malignant tra nsformation of pre-existing benign tumours, The apparent rarity of los s of heterozygosity (LOH) reported for benign tumours has led to specu lation that they lack malignant potential and represent a biological e ntity distinct from ovarian carcinoma, We reasoned that the absence of detectable LOH may be due to the masking of such losses by contaminat ion with normal tissue present in excess in the majority of benign tum our biopsies, Therefore we utilized a microdissection technique to exa mine for LOH using 14 microsatellite markers on chromosome arms 6q, 7p , 7q, 9p, 11q and 17p in 31 solitary benign epithelial ovarian tumours , LOH was detected on all chromosome arms with the most frequent LOH o ccurring on 7p (27%) and 9p (26%), In addition, a point mutation in co don 157 of TP53 was detected in one tumour which is the first report o f a TP53 mutation in a solitary benign ovarian tumour, In total 48% of tumours harboured genetic alterations which supports the idea that al l benign ovarian tumours may carry a genetic predisposition to maligna ncy and are therefore not inherently different from their malignant co unterparts.