Clinical significance of cyclooxygenase-2 expression in extranodal natural killer (NK)/T-cell lymphoma, nasal type

Purpose: To determine whether there are any differences in therapeutic response, patterns of systemic recurrence, and prognosis of patients with extranodal natural killer (NK)/T-cell lymphoma, nasal type, by the cyclooxygenase-2 (COX-2) expression. Patients and Methods: Thirty-four patients with Ann Arbor Stage I and II extranodal NK/T-cell lymphoma who underwent chemotherapy or radiotherapy, or both, were retrospectively reviewed. These patients were divided into two groups according to their immunohistochemical staining for COX-2 expressions: a COX-2-negative group (n = 10 patients) and a COX-2-positive group (n = 24 patients). The treatment response, patterns of treatment failure, and survival data for the patients were compared between the COX-2-positive and negative groups. Results: There was no significant difference in the clinical profiles between the COX-2-negative and COX-2-positive groups. All patients (100%) in the COX-2-negative group achieved complete response after initial treatment, whereas only 14 patients (58%) in the COX-2-positive group achieved complete response (p = 0.03). Compared with the patients in the COX-2-negative group, those in the COX-2-positive group had a significantly lower 2-year systemic recurrence-free survival rate (100% for the COX-2-negative group vs. 54% for the COX-2-positive group) (p = 0.02) and a decreased 5-year overall survival rate (70% for the COX-2-negative group vs. 32% for the COX-2-positive group) (p = 0.06). Conclusion: Cyclooxygenase-2 expression can serve as a predictive factor for poor treatment response, higher systemic recurrence, and unfavorable prognosis in patients with extranodal NK/T-cell lymphoma, nasal type.