Expression of ki67 in papillary thyroid microcarcinoma and its clinical significance.

PURPOSE To investigate the expression of Ki67 protein in papillary thyroid microcarcinoma(PTMC), and to analyze its clinical significance. MATERIALS AND METHODS Ki67 protein expression was evaluated in the tissues of 108 human PTMC and 50 other benign papillary hyperplasia of thyroid specimens using immunohistochemistry. RESULTS The expression intensity of Ki67 in PTMC and benign papillary hyperplasia of thyroid specimens were 1.45±1.83% and 0.46±0.46%.The positive expression rates were 46.3% and 14%. There were significant differences between these two groups (p<0.01). There was no significant variation of the expression intensity and positive expression rates of Ki67 in PTMC with gender, age, position of the tumor and the level of TSH pre-operation (p>0.05), but these parameters varied with tumor size, invasion by membrane and cervical lymph node metastasis (p<0.05 or p<0.01). CONCLUSIONS The expression of Ki67 in PTMC was related to tumor size, invasion by membrane and cervical lymph node metastasis, and could be the important indicator for judging clinical progress and estimating prognosis.