Tumor size and clinical stage are independent risk predictors for the high occurrence and poor prognosis of postoperative liver metastasis in patients with radically resectable pancreatic cancer

There is no detailed data for illustrating the predictors that influence the occurrence and prognosis of postoperative liver metastasis (PLM) in patients with radically resectable pancreatic cancer (PC). 189 consecutive non-metastatic PC patients and 20 nude mice were entered into this study. We retrospectively determined the clinical factors that influenced the occurrence and prognosis of PLM, and constructed liver metastasis models in vivo for further biology research. PC recurred in 145 (76.7%) of the 189 patients, and 68 cases occurred in liver metastasis (46.8%). Its occurrence was positively associated with tumor size, T stage, lymph metastasis (classified as UICC stage IIB) and UICC stage (IA+IB vs. IIA+IIB). Multivariate analysis identified tumor size >= 3.5 cm (P = 0.005), lymph metastasis (P = 0.032) and UICC stage (P = 0.021) as independent risk factors for PLM. Meanwhile, PLM was an independent unfavorable prognostic indicator for the survival of 189 PC patients. Tumor size (P = 0.024) and lymph metastasis (P = 0.026) were independent risk prognostic indicators in 68 patients with PLM. In vivo, high incidence of liver metastasis was found in nude mice implanted with PC cells in both spleen and tail vein injected manners (100% and 80%). Meanwhile, tumor size and number of liver metastases were closely associated with the poor survival of nude mice. Tumor size and clinical stage are independent risk indicators for the high occurrence and poor prognosis of PLM in PC patients. Two liver metastasis models further reveal the aggressive biology of tumor size-and number-dependent liver metastasis in PC.