The epidermal growth factor receptor status in anaplastic thyroid carcinoma

Abstract

Background and objectives: The epidermal growth factor receptor (EGFR) has been reported to be overexpressed in anaplastic thyroid carcinoma (ATC) and in vitro studies have showed that EGFR tyrosine kinase inhibitors (TKIs) greatly inhibited cellular growth and induced apoptosis in the ATC cell lines, while somatic mutations in the tyrosine kinase domain or an increased gene copy number are associated with increased sensitivity to TKIs in non-small cell lung cancer. Methods: We investigated the EGFR gene status and protein expression by direct DNA sequencing of the hot-spot regions in exons 18, 19 and 21, fluorescence in situ hybridization (FISH), and immunohistochemistry in tumor tissues from 23 patients with ATC.

Results: On mutational analysis and FISH, neither mutations in the hot-spots nor gene amplification was observed. Yet, high polysomy was identified in 14 (60.9%) of 23 patients with ATC. All cases with IHC positivity (n=6) had high polysomy, whereas 8 (47.1%) out of the 17 cases with IHC negativity had high polysomy (P=0.048).

Conclusion: Despite the low incidence of somatic EGFR gene mutation and amplification in our study samples, when considering that high polysomy was often identified by FISH as well as the current lack of therapeutic options, EGFR TKIs are worth investigating for treating the patients with ATC.