Chromosomal numerical aberrations are frequent in oesophageal and gastric adenocarcinomas:: a study using in-situ hybridization

Aims (i) To investigate and compare the numerical aberrations of chromosomes 7, 8, 11, 17 and Y in a series of 60 adenocarcinomas of the oesophagus, gastric cardia and gastric antrum; and (ii) to specify the sequence of chromosomal aberrations occurring during the neoplastic progression of Barrett's oesophagus. Methods and results: Chromosomal in-situ hybridization was performed on deparaffinized tissue sections from 20 Barrett's adenocarcinomas, 20 adenocarcinomas of the cardia and 20 adenocarcinomas of the antrum, with centromeric alpha satellite DNA probes specific for chromosomes 7, 8, 11, 17 and Y, labelled with digoxigenin. Signals were detected by immunoperoxidase staining. The copy number for each chromosome was counted in 200 tumour cells nuclei and 100 lymphocytes as controls. In parallel, the DNA content of the nuclear suspensions was measured by flow cytometry. Numerical abnormalities of the five chromosomes (loss of the Y chromosome, monosomy, trisomy, and tetrasomy) were frequently observed in the three groups of adenocarcinomas (from 40% to 65% of the cases). Sixty per cent to 75% of oesophagus and gastric adenocarcinomas were DNA-aneuploid. Chromosomal aberrations progressively increased with advancing degrees of dysplasia in Barrett's mucosa, with an increasing frequency of trisomy and loss of the Y chromosome from non-dysplastic Barrett's mucosa to invasive adenocarcinoma, and with monosomy and tetrasomy present only in invasive cancers. Conclusions: Our study confirms the high frequency of chromosomal numerical aberrations in oesophageal and gastric adenocarcinomas, without differences between adenocarcinomas of the gastric cardia and antrum. We have shown that these alterations occur early during the neoplastic transformation of Barrett's mucosa.