In REACT, celecoxib treatment (400 mg daily for 2 years) in a subgroup of 655 breast cancer patients who did not receive chemotherapy reduced the hazard ratio for recurrence over 10 years by 35% (HR = 0.65, 95% confidence interval 0.41–1.04, P = 0.035 by a one-tailed test of significance). These results underscore the importance of further testing of celecoxib in patients with early-stage breast cancer who are not treated by chemotherapy.