A substantial fraction of patients develop overt metastases soon after resection of primary breast tumours, but the cause of this metastatic relapse remains undefined. In a mouse model of tumour dormancy, Krall et al. show that the surgical wounding required for tumour resection induces a systemic inflammatory response that can trigger the outgrowth of breast cancer tumours at distant anatomical sites, which was otherwise restricted by a tumour-specific T cell response. Perioperative treatment of the mice with the anti-inflammatory drug meloxicam significantly reduced tumour growth.