Preventing recurrence of non-muscle-invasive bladder cancer (NMIBC) is important for improving patient well-being and reducing the health economic burden of this disease. To date, no oral agent has shown sufficient benefit to be adopted in clinical practice, where current strategies rely on topical (intravesical) administration of chemotherapy and immunotherapy. In this issue of the journal (beginning on page 1580), Sabichi and colleagues report the first phase II randomized controlled trial of the COX-2 inhibitor celecoxib in bladder cancer. The trial set out to measure an overly ambitious effect size but nevertheless showed encouraging signs of celecoxib activity. It lends support to COX-2 inhibition in NMIBC, which is being tested in several subsequent trials, and to the need for conclusive evidence.