LOSS OF HETEROZYGOSITY ON CHROMOSOMES 7P, 7Q, 9P AND 11Q IS AN EARLY EVENT IN OVARIAN TUMORIGENESIS

Forty early stage malignant and seven borderline ovarian tumours mere analysed for loss of heterozygosity (LOH) on chromosomes 6, 7, 9, 11 a nd 7, LOH involving at least one locus was observed in 32 (80%) early stage and six (86%) borderline tumours, Frequent LOH in the early stag e tumours was detected on chromosome arms 7p (31%), 7q (50%), 9p (42%) and 11q (34%) suggesting that these chromosomes harbour tumour suppre ssor genes which are inactivated early in tumorigenesis, Borderline tu mours exhibited a similar pattern of LOH to that observed in the early stage malignant tumours, indicating that the development of both mali gnant and borderline forms may involve inactivation of the same set of tumour suppressor genes. Together with our previous investigation of benign ovarian tumours this data supports the theory that malignant ov arian tumours may arise from benign and borderline precursors.