Analysis of ovarian borderline tumors using comparative genomic hybridization and fluorescence in situ hybridization

It is unclear whether ovarian borderline tumors (tumors of low malignant po tential) are independent entities or whether they are part of a continuum o f tumor progression that culminates in ovarian carcinoma. Little is known a bout genetic abnormalities in borderline tumors because of the difficulty o f growing them in culture for chromosome studies, and because the low ratio of tumor to nontumor cells can interfere with molecular genetic examinatio n. To circumvent these problems, we performed comparative genomic hybridiza tion (CGH) on 10 serous borderline tumors from nine patients, using microdi ssection to enrich the samples for tumor DNA and reduce contamination from stromal and inflammatory cells. CGH analysis revealed that three of the tum ors had detectable chromosomal imbalances, whereas seven were in a balanced state. In those tumors with imbalances, the number of abnormalities ranged from 3-6 per tumor. Additional studies by fluorescence in situ hybridizati on (FISH) on disaggregated nuclei confirmed the imbalances detected by CCH, revealed one tumor to be hypeptriploid, and indicated that the remaining t umors were diploid and in a balanced state. All abnormalities observed in t he aneuploid cases are consistent with chromosomal aberrations previously r eported for ovarian carinomas, providing further evidence that some borderl ine tumors are part of a continuum of tumor progression. These results also suggest that there may be different mechanisms leading to borderline tumor formation, including one associated with multiple chromosomal imbalances, and others that do not involve imbalances detectable by CGH, Genes Chromoso mes Cancer 25:307-315, 1999. (C) 1999 Wiley-Liss, Inc.