PTGS2 and breast carcinoma: The Randomized European Celecoxib Trial (REACT) was a phase 3, multicenter, double-blind, placebo-controlled randomized clinical trial evaluating the selective cyclooxygenase-2 (COX-2) inhibitor celecoxib (400 mg daily for 2 years) as adjuvant therapy for 2,639 patients with early-stage primary breast cancer (1).