Objective: The purpose of this analysis is to determine whether a significant correlation exists between cyclooxygenase-2 (COX-2) expression and local relapse in a large cohort of patients with T1 to 2N0 laryngeal cancer treated with primary radiation therapy.
Methods and materials: Clinical and molecular analyses were conducted on 123 patients with biopsy-proven T1 to 2N0 laryngeal cancer. Clinical prognostic factors included pretreatment hemoglobin, age, sex, race, T stage, tumor subsite, beam energy, biologically equivalent dose, therapy duration, and treatment date. Molecular prognostic factors included COX-2, p53, and Ki-67 expression. Expression levels were determined by immunohistochemistry on paraffin-embedded tissues arrayed on tissue microarrays. Multivariate analysis was done with the Cox proportional hazards model.
Results: Thirty-two patients have locally relapsed, for an actuarial 5-year local relapse-free rate of 70.4%. On multivariate analysis, positive COX-2 expression predicted local relapse after radiation therapy. The relative risk (RR) for local relapse with COX-2 positivity was 2.57 (95% CI, 1.21-5.47; P = .01). Other prognostic factors for local relapse included negative Ki-67 expression (RR = 5.72; 95% CI, 2.04-16.1; P < .001), T2 stage (RR = 2.98; 95% CI, 1.39-6.38; P = .005), and therapy duration greater than 43 days (RR = 6.04; 95% CI, 1.37-26.7; P = .02).
Conclusions: Positive COX-2 expression predicts for local relapse in T1 to 2N0 larynx cancer in a multivariate model. This relationship may have potential therapeutic implications regarding the use of COX-2 inhibitors during radiation therapy for optimal outcome.