PCR AMPLIFICATION AND ANALYSIS OF RAS ONCOGENES FROM THYROID CYTOLOGIC SMEARS

Fine needle aspiration (FNA) cytology represents a reliable diagnostic procedure for preoperative identification of thyroid carcinoma. For i mproving its diagnostic accuracy, a technique that allows the analysis of cancer-related gene abnormalities on thyroid FNA smears has been d eveloped. Cells were collected by scraping from thyroid smears, DNA-ex tracted and ras proto-oncogene sequences amplified by the polymerase c hain reaction (PCR). Preliminary destaining of cytologic smears was es sential for efficient PCR amplification. Twelve thyroid FNA cytologic smears, characterized by the indeterminate pattern of follicular neopl asia, were analysed for the presence of ras mutations known to confer an oncogenic potential. The same nucleotide substitution at codon 12 o f the H-ras proto-oncogene was detected in two different thyroid nodul es among six cases that, at final histology, were identified as follic ular carcinomas. No ras mutations were observed in the remaining six c ases that were diagnosed as follicular adenoma at histologic examinati on. Molecular analysis of FNA smears may provide additional informatio n on the nature of the lesion underlying thyroid neoplasia, thus impro ving diagnostic accuracy of conventional FNA cytology.