Proliferative activity of human thyroid tumors evaluated by proliferating cell nuclear antigen/cyclin immunohistochemical studies

BACKGROUND: To clarify the proliferative activity of human thyroid tumors, the labeling index of various thyroid tumors was evaluated by proliferating cell nuclear antigen (PCNA)/cyclin immunostaining. METHODS: Surgically removed thyroid carcinoma, adenoma, adenomatous goiter, normal thyroid, and breast carcinoma were used for the study. Small pieces of tissue from the surgical materials were fixed in Methacarn solution (methanol-chloroform-acetic acid = 6:3:1) (Wako junyaku Co., Osaka, Japan) and embedded in paraffin. Sections were stained with PCNA/cyclin monoclonal antibody. RESULTS: The reaction product for PCNA/cyclin was observed mainly on nuclei. The ratio of the PCNA/cyclin-positive nuclei to the total number of nuclei was compared among the tumors. Ratios of PCNA/cyclin-positive nuclei were 4.9% in well-differentiated papillary carcinoma of the thyroid, 4.6% in poorly differentiated papillary carcinoma of the thyroid, 3.6% in thyroid follicular carcinoma, 1.9% in adenomatous goiter, 2.0% in thyroid follicular adenoma, and 0.6% in normal thyroid tissues. CONCLUSIONS: It was shown in this study that the ratio of PCNA/cyclin-positive nuclei reflects the relative clinical behavior of thyroid tumors.