Expression Of Mcl-1 And Ki-67 In Papillary Thyroid Carcinomas

Studying molecules that are differentially expressed in cancers as well as benign and normal tissues is crucial for identifying novel bio-markers for cancer immunotherapy. This study aimed to investigate the clinical utility of the immunochemical expression of the proliferative cell marker Ki-67 and the apoptotic blocker Mcl-1 in papillary thyroid carcinoma (PTC). Methods: We built a tissue microarray with 282 thyroid specimens. There were 59 PTCs including 35 classic (CPTC), 3 tall cell (TCPTC) and 21 follicular variants (FVPTC); 79 benign thyroid diseases (22 follicular adenomas; 57 adenomatoid hyperplasia); 33 Hashimoto's thyroiditis (HT) specimens; and 111 normal thyroid tissues. Clinical history and ultrasound data were retrospectively obtained by chart review. Results: Mcl-1 overexpression was evident in 66.7% of the PTC tissues compared to 32% of the benign thyroid diseases. Mcl-1 strong staining distinguished benign from malignant thyroid lesions (sensitivity = 61.3%; specificity = 72.8%; negative predictive value, NPV = 68%; positive predictive value, PPV = 66.7% and 67.5% accuracy). Positive nuclear Ki-67 staining was observed in 34% of PTCs vs. 19% of thyroid adenomas (P = 0.031). Strong Mcl-1 and Ki-67 co-expression was identified in 57.5% of PTCs with a higher PPV (75.8%). Mcl-1 and Ki-67 expression was not associated with any clinicopathological feature of malignancy. No deaths occurred during the follow-up. Conclusions: Mcl-1 immunochemical overexpression allowed differentiating low-risk PTC from the benign thyroid lesions. We suggest that Mcl-1 expression may help differentiate follicular patterned thyroid lesions. The influence of the Mcl-1 expression on several features of tumor aggressiveness has to be studied in large series of high-risk thyroid carcinomas.12420921