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Cyclooxygenase 2 expression in nasopharyngeal carcinoma: immunohistochemical findings and potential implications
  1. K-B Tan1,
  2. T C Putti2
  1. 1Department of Pathology, National University of Singapore, Lower Kent Ridge Road, Singapore 119074
  2. 2Department of Pathology, National University of Singapore
  1. Correspondence to:
 Dr K-B Tan
 Department of Pathology, National University of Singapore, Lower Kent Ridge Road, Singapore 119074;


Background: Cyclooxygenase 2 (COX-2), an inducible prostaglandin synthase, participates in inflammatory and neoplastic processes. It is expressed by various tumours and contributes to carcinogenesis. Notably, COX-2 inhibitors appear to have tumour suppressor effects and are being evaluated in clinical trials.

Aims: To investigate COX-2 expression in nasopharyngeal carcinoma (NPC), a common tumour in parts of Asia, and to discuss potential implications.

Methods: Eighty five cases of NPC were reviewed. COX-2 immunohistochemistry and semiquantitative assessment of expression in nasopharyngeal biopsies were performed. Because COX-2 is proangiogenic, tumour microvessel density was also assessed with the use of CD31 immunohistochemistry.

Results: Histologically, 78 NPCs were undifferentiated, six were non-keratinising, and one was keratinising. Thirty nine NPCs had adjacent dysplastic epithelium. COX-2 expression was noted in 60 NPCs, 14 of 39 samples of dysplastic epithelium, and only one of 25 samples of normal epithelium (p < 0.01). Microvessel density was not significantly different between COX-2 positive and COX-2 negative tumours (p  =  0.774). Tumour COX-2 positivity was not associated with higher tumour stage (p  =  0.423).

Conclusion: COX-2 expression is more frequently seen as nasopharyngeal epithelium progresses from normal to dysplastic to carcinoma. This suggests that COX-2 contributes to the multistep process of NPC carcinogenesis. COX-2 represents a therapeutic target for COX-2 inhibitors, and there is thus a basis for the further investigation of this adjuvant treatment modality for NPC. COX-2 inhibitors are known to potentiate the antitumour effects of radiotherapy, which is the primary treatment for NPC.

  • COX, cyclooxygenase
  • EBV, Epstein-Barr virus
  • MVD, microvessel density
  • NPC, nasopharyngeal carcinoma
  • nasopharyngeal carcinoma
  • cyclooxygenase
  • head and neck
  • undifferentiated carcinoma
  • upper aerodigestive tract

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  • This study was presented orally at Pathology Update 2004, annual meeting of the Royal College of Pathologists of Australasia, held in Sydney, Australia, 12–14 March 2004.