Expression of cytokeratin 20 in thyroid carcinomas and peripheral blood detected by reverse transcription polymerase chain reaction

We investigated a nested reverse transcriptase polymerase chain reaction (R T-PCR) system to detect CK20 mRNA in thyroid carcinomas, benign thyroid dis eases and peripheral blood to improve diagnosis of thyroid carcinoma and to detect disseminated tumour cells. Frozen tissue samples of 46 thyroid carc inomas and 30 benign thyroid diseases (14 multinodular goiters, 14 follicul ar adenomas, two Hashimoto's thyroiditis) were obtained intraoperatively. P reoperative blood samples were drawn from 31 patients with thyroid cancer, nine patients with benign thyroid disorders and 20 healthy volunteers. Nine out of nine medullary, 9/12 follicular, 7/19 papillary and 2/6 anaplastic carcinomas expressed CK20 transcripts. CK20 mRNA was undetectable in 30 tis sue sections of benign thyroid diseases. Circulating tumour cells were foun d in the blood of 3/8 patients with medullary carcinoma, 2/8 patients with follicular carcinoma, 2/11 patients with papillary carcinoma and 1/4 patien ts with an anaplastic carcinoma. Nine blood samples of patients with benign thyroid diseases and 20 healthy volunteers tested negative. For the first time CK20 mRNA could be detected in tissue sections of thyroid carcinomas a nd peripheral blood samples of patients with thyroid cancer. It was not det ectable in benign thyroid diseases. Our results therefore strongly suggest that CK20 RT-PCR assays may improve the diagnosis of thyroid carcinoma and is able to detect circulating tumour cells in peripheral blood of thyroid c arcinoma patients. (C) 2000 Cancer Research Campaign.