Screening for genetic aberrations in papillary thyroid cancer by using comparative genomic hybridization

Determination of the genetic composition of papillary thyroid cancers may help explain differences in observed clinical behavior. Comparative genomic hybridization (CGH) is a novel molecular cytogenetic assay that allows simultaneous detection of gains, losses, and amplification of genetic information, making it an ideal screening tool. The aim of this study was to identify genetic aberrations occurring in papillary thyroid cancers by using CGH analysis.

CGH analysis was performed on 21 individual cases of papillary thyroid cancers. Nonparametric statistical comparisons were performed with the Fisher exact test.

Genetic abnormalities were identified by CGH in 10 of 21 cases (48%). A recurrent pattern of aberrations was seen in cases where genetic changes were detected, involving losses at chromosome arms 1p and 9q and chromosomes 17, 19, and 22, and gains at chromosome 4 and chromosome arms 5q, 6q, 9q, and 13q. The loss of chromosome 22 was unique to younger patients (P =.05) and was associated with a higher rate of regional lymphatic metastasis (19% vs 80%, P =.02).

Two genetically unique groups of patients were identified by using CGH analysis. One group had no detectable aberrations; the other had a recurrent pattern of aberrations, localizing to the identical chromosomal loci. This pattern of aberrations suggests that the involved loci may contain genes important in thyroid carcinogenesis. The clinical significance of the presence of copy number changes detected by CGH needs to be determined. In addition, molecular cloning of involved genes in each of the aberrations is warranted.