Low frequency of numerical chromosomal aberrations in follicular thyroid tumors detected by comparative genomic hybridization

Follicular thyroid tumors vary from adenomas to widely invasive carcinomas, and a stepwise progression from normal thyrocyte to malignant tumor has be en suggested to be due to an accumulation of genetic alterations. We have u sed comparative genomic hybridization to screen 21 follicular thyroid tumor s (8 adenomas and 13 carcinomas) for gains and losses of DNA sequence copy numbers. In general, the tumors showed few alterations involving several di fferent chromosomal regions. The frequency of alterations was similar in th e benign (mean, 1.9) and malignant (mean, 1.5) tumors, as well as in minima lly (mean, 1.5) and widely invasive carcinomas (mean, 1.6). However, specif ic loss of 9q13-q21.3 was detected in three tumors, which were all carcinom as showing oxyphilic changes (Hurthle cell carcinomas; P = 0.003). The fact that DNA copy number alterations were found with a similarly low frequency in both benign and malignant follicular thyroid tumors does not support th e hypothesis of a multistep tumor progression in these tumors. Genes Chromo somes Cancer 25:349-353, 1999. (C) 1999 Wiley-Liss, Inc.