FREQUENT LOSS OF CHROMOSOME-22 IN HUMAN EPITHELIAL OVARIAN-TUMORS - ACHROMOSOMAL IN-SITU HYBRIDIZATION STUDY

The short arm isochromosome of chromosome 12 and trisomy 12 are well-e stablished chromosomal alterations in human ovarian germ cell tumors. However, numerical aberrations of chromosome 12 in epithelial ovarian tumors (EOTs) are highly controversial: both trisomy 12 and monosomy 1 2 have been observed. We performed chromosomal in situ hybridization i n paraffin-embedded and formalin-fixed tissue sections of 31 EOTs. Twe nty-five EOTs could be evaluated statistically (2 mucinous, 11 serous, 5 endometrioid, 3 borderline, and 4 other epithelial-type tumors) to examine the copy number of chromosome 12 and 15. The frequency distrib ution of hybridization signals with alpha-satellite centromeric DNA pr obes for chromosome 15 revealed disomy in all cases. However, we found the loss of chromosome 12 in 16 of 25 tumor samples. No correlation w as found between the presence of monosomy 12 and the clinical stage of the tumors. Frequent loss of chromosome 12 may indicate that this chr omosome is involved in the tumorigenesis of EOTs. Further studies are needed to clarify whether loss of chromosome 12 is an early or late ev ent in ovarian carcinoenesis.