Proliferating cell nuclear antigen (PCNA) in medullary thyroid carcinoma

We investigated the expression of proliferating cell nuclear antigen (PCNA) in paraffin sections from 20 cases of medullary thyroid carcinoma (MTC). Follow-up data were available in eleven cases. PCNA index positively correlated with the degree of cellular pleomorphism (grade) of the tumor (p<0.01), the pathologic state (p<0.01) and the poor clinical outcome (p<0.05). These findings suggest that PCNA may be of prognostic significance in MTC.