Cyclooxygenase 2 expression in nasopharyngeal carcinoma: immunohistochemical findings and potential implications.
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.


OBJECTIVE
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).


CONCLUSIONS
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.
Tan
K-B
KB
Department of Pathology, National University of Singapore, Lower Kent Ridge Road, Singapore 119074. pattankb@nus.edu.sg
Putti
T C
TC
D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D002278:Carcinoma in Situ / Q000098:blood supply / Q000737:chemistry; D002294:Carcinoma, Squamous Cell / Q000098:blood supply / Q000737:chemistry; D051546:Cyclooxygenase 2; D004848:Epithelium / Q000737:chemistry / Q000473:pathology; D004854:Herpesvirus 4, Human / Q000302:isolation & purification; D006801:Humans; D007150:Immunohistochemistry / Q000379:methods; D007633:Keratins / Q000378:metabolism; D008565:Membrane Proteins; D008833:Microcirculation; D008875:Middle Aged; D009303:Nasopharyngeal Neoplasms / Q000098:blood supply / Q000737:chemistry*; D009367:Neoplasm Staging; D010544:Peroxidases / Q000378:metabolism; D011451:Prostaglandin-Endoperoxide Synthases / Q000032:analysis*
D008565:Membrane Proteins; D007633:Keratins; D010544:Peroxidases; D051546:Cyclooxygenase 2; C496540:PTGS2 protein, human; D011451:Prostaglandin-Endoperoxide Synthases