['Colorectal cancer (CRC) is the third leading cause of cancer death in Japan. CD10 expression is closely associated with liver metastasis. In the present study, we explored the possibility of serum CD10 as a marker of liver metastasis in CRC.', 'BALB/c mouse with subcutaneous tumor of syngeneic CT26 CRC cells were examined serum CD10. In 84 CRC patients and patients undergoing hemodialysis, serum CD10 was examined. CD10 concentration was measured by enzyme-linked immunosorbent assay.', 'In a mouse subcutaneous tumor model, serum CD10 correlated with the weight of the tumors. Serum CD10 was examined in 84 patients with CRC. The serum levels of CD10 were higher in patients with more advanced cancer stages. Patients with liver metastasis showed the highest levels of serum CD10 among all patients. Importantly, patients with high serum CD10 levels had metachronous liver metastasis. Healthy volunteers showed low levels of CD10; however, serum CD10 levels in patients undergoing hemodialysis showed levels as high as those with stage II and III CRC. A cutoff of serum CD10 set to >1000 pg/mL showed 70% sensitivity and 93% specificity for liver metastasis in CRC. This cutoff included all cases of metachronous liver metastasis.'] Is serum CD10 associated with liver metastasis in colorectal cancer?