Is there a benefit for patients who receive celecoxib as an addition to conventional therapy for women with ERBB2 (formerly HER2)–negative primary breast cancer? A report on the Randomized European Celecoxib Trial (REACT), a phase 3, randomized, double-blind study conducted in 160 centers across the UK and Germany testing two years of adjuvant celecoxib vs. placebo among 2,639 patients recruited between 2007 and 2012, with follow-up 10 years after treatment completion.