Further support for an effect of aspirin on micrometastases derives from 5 different randomized trials of aspirin for the prevention of vascular events that showed that aspirin use (80–325 mg/day) decreased the risk of metastases from CRC at diagnosis, as well as the risk of subsequent metastasis at follow-up in patients who were initially metastasis-free (HR=0.26; 95% CI 0.11–0.57; P=0.0008)(31)