Recurrent chromosome aberrations in human lung squamous cell carcinomas

Cytogenetic study of seven cases of previously untreated lung squamous cell carcinomas (SQC) is reported. Chromosome numbers vary from 38 to 538, with a majority of hypotriploid karyotypes with complex rearrangements. The numbers of recurrent imbalances were evaluated in considering the average number of chromosomes or chromosome segments in each analyzed metaphase and for each case. In decreasing order of frequency, deficiencies for 3p, 5q, 8p, Y, 5p, 10p, 13, and, to a lesser degree, for 8q, 9, 10q, 11pter, 14, 15, and 21 were observed; the excesses principally involve 1q, 3q, and 7q. In three tumors, homogeneously staining regions were observed at various chromosome sites. Most chromosome rearrangements occurred after breakage in constitutive heterochromatin, and no recurrent breakpoints were found in euchromatin except 11p15. The major consequences of these anomalies may be chromosomal imbalances, leading to hemizygosity and perhaps related to gene dosage, rather than to alterations of genes.