PROLIFERATIVE ACTIVITY OF HUMAN THYROID-TUMORS EVALUATED BY PROLIFERATING CELL NUCLEAR ANTIGEN CYCLIN IMMUNOHISTOCHEMICAL STUDIES

Background. To clarify the proliferative activity of human thyroid tum ors, the labeling index of various thyroid tumors was evaluated by pro liferating cell nuclear antigen (PCNA)/cyclin immunostaining. Methods. Surgically removed thyroid carcinoma, adenoma, adenomatous goiter, no rmal thyroid, and breast carcinoma were used for the study. Small piec es of tissue from the surgical materials were fixed in Methacarn solut ion (methanol-chloroform-acetic acid = 6:3:1) (Wako junyaku Co., Osaka , Japan) and embedded in paraffin. Sections were stained with PCNA/cyc lin 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. Ra tios of PCNA/cyclin-positive nuclei were 4.9% in well-differentiated p apillary carcinoma of the thyroid, 4.6% in poorly differentiated papil lary 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 t hat the ratio of PCNA/cyclin-positive nuclei reflects the relative cli nical behavior of thyroid tumors.