Cyclooxygenase-2 expression in nasopharyngeal carcinoma

Abstract

Purpose/Objective(s): Cyclooxygenase-2 (COX-2) expression in tumor and epithelium was evaluated before and during radiotherapy (RT) for nasopharyngeal carcinoma (NPC). Materials/Methods: 53 patients (36 males and 17 females) with NPC had tumor biopsy performed before RT. Except for 1 well differentiated squamous cell carcinoma (1.9%), all others were poorly differentiated or undifferentiated carcinoma (98.1%). Neighboring non-malignant epithelium was found in 43 of the pre-RT biopsies. 43 patients had another NP biopsy after 2–3 weeks of RT but 14 did not have tumor in the second biopsy. Normal epithelium was assessable in 39 of the second biopsy. The intensity and extent of COX-2 expression in tumor and epithelium were evaluated with immunohistochemical staining. Results: The number of patients with stage I, II, III and IV disease were 6, 15, 13 and 19, respectively. All patients had RT, 24 patients also had cisplatin concurrent with RT. For the pre-RT biopsies, only 7.5% tumors showed no COX-2 expression compared with 65.1% of epithelium. 28.3% of tumor had no to mild COX-2 staining compared with 83.7% in neighboring epithelium. 71.7% of tumor had moderate to intense COX-2 staining compared with 16.3% in the epithelium. The 3 epithelium which showed intense staining for COX-2 were all dysplastic. There was similar difference in the extent of COX-2 staining between tumor and the epithelium. 37.7% of tumor showed\10% positive staining compared with 90.7% of epithelium. 62.3% of tumor showed at least 10% positive staining compared with 9.3% in epithelium. After 2–3 weeks of RT/chemoRT, 32.6% of the repeat biopsies showed no tumor. Of the 29 biopsies that had tumor cells, the intensity of COX-2 staining in tumor cells remained unchanged in 37.9%, decreased in 34.5% and increased in 27.6%, compared with their pre-RT biopsies. Similarly, the extent of COX-2 staining in tumor showed no change in 48.3%, decreased in 34.5% and increased in 17.2% in the second biopsy. 32 patients had assessable epithelium in both biopsies. Compared with the pre-RT biopsy, there was no change in intensity and extent of COX-2 staining in the epithelium in 43.8%, increased in 28.1% and decreased in 28.1% of the second biopsies. There was no correlation between COX-2 expression in tumor with stage or outcome after treatment (Table). Conclusions: COX-2 overexpression was commonly observed in NPC but not in neighboring non-malignant epithelium. After 2– 3 weeks of RT, 32.6% of biopsy turned negative and another 34.5% of tumor showed reduced COX-2 expression. The intensity and extent of COX-2 staining in tumor and neighboring non-malignant epithelium before and after 2 to 3 weeks of RT.