Objective: Approximately 30% of patients with thyroid nodules have indeterminate, nondiagnostic, or suspicious fine-needle aspiration (FNA) biopsy results. These patients usually undergo thyroidectomy because of cancer risk. Our aim was to determine diagnostic markers to distinguish benign from malignant thyroid neoplasms, so we focused on G2-M boundary regulators of the cell cycle and investigated the expression of two proteins, cyclin A and cyclin B1.
Methods: We studied the expression of cyclin A and B1 in resection specimens of 168 indeterminate, nondiagnostic, or suspicious FNA biopsy results retrospectively using immunohistochemistry.
Results: Sixty-four of resection specimens were consisted of malignant histopathology. Of 64 cases of thyroid cancer (58 papillary, 4 follicular, 1 medullary, and 1 hürthle cell carcinoma), cyclin A was overexpressed in 33 cases (51.5%) in contrast to 33 cases (31.7%) of 104 benign pathology specimens (P=0.025). Tweny-five (39.1%) of thyroid cancer cases were positive for cyclin B1 in contrast to 16 (15.4%) of 104 benign cases (P=0.001). Cyclin A overexpression was not linked to cyclin B1 overexpression. No association was found between overexpressions of cyclin A, cyclin B1 and TNM stage in malignant cases.
Conclusions: In this study, we have demonstrated that cyclin A and B1 may be important biomarkers in predicting malignancy in indeterminate, nondiagnostic, or suspicious FNA biopsies. The use of these biomarkers may allow an accurate preoperative diagnosis of thyroid cancer. The value of these biomarkers warrants further evaluation in a prospective study on fresh cytological samples of indeterminate, nondiagnostic, or suspicious FNA biopsies.