Cyclin D1, RET and p27 Expression in Papillary Thyroid Microcarcinoma

Th e aim of the study was to determine the influence of RET, p27 and cyclin D1 on regional lymph node metastases in papillary microcarcinoma. The analysis included 70 patients with papillary thyroid microcarcinoma that underwent surgery at Split University Hospital Center between 1999 and 2001. Immunohistochemistry was performed on formalin-fixed, paraffin-embedded tissue by the RET, p27 and cyclin D1 antibodies. Quantification was based on the intensity and distribution of nuclear staining, dividing tumors into those that showed expression (expressors) and those that showed no expression (non-expressors). Univariate analysis using χ²-test and Fisher exact test was performed with the level of statistical significance set at p<0.05. There was no statistically significant difference in the incidence of metastases according to the expression or non-expression of RET mutation (χ²-test: p=0.459; Fisher exact test: p=0.672). Among 25 cases with cyclin D1 expression, 6 had metastases, whereas only 2 of 45 cases with no cyclin D expression had metastases (χ²-test: p=0.014; Fisher exact test: p=0.021), indicating that the expression of cyclin D1 is not crucial for the development of metastases in lymph nodes. In contrast, analysis of p27 expression showed it to be significantly associated with lymph node metastasis because 3 of 45 patients with p27 expression had metastases, indicating a statistically significant correlation between p27 expression and lymph node metastases (χ²-test: p=0.093; Fisher exact test: p=0.124). This study confirmed the importance of the evaluation of RET, p27 and cyclin D1 expression and demonstrated the validity of their application in the assessment of microcarcinoma behavior.