Abstract: Objective To explore the relationship between abnormal expressions of positive cell cycle control factors and thyroid
carcinoma occurrence and progression, and assess the value of these factors in evaluating tumor cell proliferation activity and
the prognosis of the patients. Methods Immunohistochemical SP method was used to detect the expressions of MCM7, CDK2
and Ki-67 proteins in 50 cases of thyroid carcinoma, 30 cases of thyroid adenoma, 30 cases of nodular goiter and 20 cases of
normal thyroid gland tissues. Results The positive rates of MCM7, CDK2 and Ki-67 expressions in thyroid carcinoma were
100% (50/50), 80.00% (40/50) and 84.00% (42/50), significantly higher than the rates in thyroid adenoma, nodular goiter and
normal thyroid tissue (P<0.01). In thyroid carcinoma tissues, positive correlations were observed between the expressions of
MCM7 and CDK2 proteins (r=0.637, P<0.01), MCM7 and Ki-67 proteins (r=0.633, P<0.01), and CDK2 and Ki-67 proteins (r=
0.862, P<0.01). Conclusion The high expressions of MCM7, CDK2 and Ki-67 protein may contribute to the development of
thyroid carcinoma, and their combined examination may serve as useful index for early diagnosis and prognostic evaluation of
thyroid carcinoma. MCM7 is superior to Ki-67 in the evaluation of the thyroid tumor cell proliferation activity.