Clinicopathological correlations of Bcl-xL and Bax expression in differentiated thyroid carcinoma

Summary Objective The Bcl‐2 family proteins are essential mediators in the apoptotic process. Our aim was to investigate whether anti‐apoptotic Bcl‐xL and pro‐apoptotic Bax were over‐expressed in a large series of differentiated thyroid carcinomas (DTC) and to study their association with tumour presentation at diagnosis and prognosis. Design and Patients We examined the immunohistochemical expression of Bcl‐xL and Bax in benign nodular thyroid disease (BNTD) and DTC and their association with clinicopathological parameters. Thyroid tissue samples were collected from an unselected series of patients undergoing surgical resection for DTC (n = 74) or BNTD (n = 15). Results Among DTC cases, expression of Bcl‐xL was found to be high in 43·2% and low or absent in 56·8%. Expression of Bax was high in 75·7% and low or absent in 24·3%. Non‐neoplastic thyroid tissue was largely unstained for both proteins. Among BNTD cases, expression of Bcl‐xL was high in 13·3% and low or absent in 86·6%. Expression of Bax was high in 14·3% and low or absent in 86·6%. A significant association was found between Bcl‐xL expression and the presence of high‐risk histological subtype (P