Clinicopathological significance of loss of p27kip1 expression in papillary thyroid carcinoma

Introduction: A meta-analysis was done to investigate the clinicopathological significance of the loss of p27(kip1) expression in papillary thyroid carcinoma (PTC). Methods: The meta-analysis involving 17 studies included 1,652 PTC and 328 benign cases. The rate of p27(kip1) expression loss in PTC and benign lesions, and the correlations between p27(kip1) expression loss and clinicopatho-logical characteristics of PTC were determined. Results: The estimated rate of p27(kip1) expression loss was 0.557 (95% confidence interval [CI] 0.443-0.665) and 0.139 (95% CI 0.062-0.283) in PTC and benign lesions, respectively. In subgroup analysis, the rates of p27(kip1) expression loss were 0.683, 0.393, and 0.414 in the classical variant, follicular variant, and papillary thyroid microcarcinoma, respectively. Loss of p27(kip1) expression was significantly correlated with lymph node metastasis and distant metastasis (odds ratio 3.559, 95% CI 1.146-11.056 and 4.735, 95% CI 1.322-16.960, respectively). Extrathyroidal extension was correlated with loss of p27(kip1) expression, but not in a statistically significant way (p = 0.051). There were no significant correlations between loss of p27(kip1) expression and sex, tumor size, BRAF(V600E) mutation, and tumor multifocality. Conclusions: Loss of p27(kip1) expression is frequently found in PTC compared with benign lesions and normal thyroid tissue. When present in PTC, it is correlated with aggressive tumor behavior.