title: Clinicopathological correlations of Bcl-xL and Bax expression in differentiated thyroid carcinoma.
abstract: 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.
  
  
  METHODS
  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 < 0.05), and regional lymph node (P < 0.01) and distant metastases (P < 0.01). The association between high Bcl-xL expression levels and a longer time of persistent disease after radioiodine ablation was also significant (P < 0.01). Bcl-xL expression was confirmed as an independent prognostic factor for persistent disease in DTC (relative risk, 2.5; 95% confidence interval, 1.1-5.9; P < 0.05).
  
  
  CONCLUSIONS
  Immunohistochemical expression of Bcl-xL might be a valuable tool in the prediction of tumour aggressiveness in DTC.
authors.affiliation: Endocrinology Unit, Hospital Universitario Virgen del Rocio, Seville, Spain.
authors.forename: M Asunción
authors.initials: MA
authors.lastname: Martínez-Brocca
authors.forename: Carolina
authors.initials: C
authors.lastname: Castilla
authors.forename: Elena
authors.initials: E
authors.lastname: Navarro
authors.forename: M José
authors.initials: MJ
authors.lastname: Amaya
authors.forename: Paulino
authors.initials: P
authors.lastname: Travado
authors.forename: Miguel A
authors.initials: MA
authors.lastname: Japón
authors.forename: Carmen
authors.initials: C
authors.lastname: Sáez
mesh_terms: D015153:Blotting, Western; D006801:Humans; D007150:Immunohistochemistry; D013959:Thyroid Diseases / Q000378:metabolism; D013961:Thyroid Gland / Q000378:metabolism / Q000473:pathology; D013964:Thyroid Neoplasms / Q000378:metabolism*; D051028:bcl-2-Associated X Protein / Q000378:metabolism*; D051020:bcl-X Protein / Q000378:metabolism*