D-dimer is an essential accompaniment of circulating tumor cells in gastric cancer

Background: Fibrinogen (FIB) is an important source of fibrin, which plays a crucial role in circulating tumor cells (CTCs) extravasation and distant metastasis development. We hypothesize it's stable final product, plasma D-dimer, may be associated with CTCs appearance and can reflect the metastatic phenotype in cancer patients. Methods: We first verified our hypothesis in different murine gastric cancer metastasis models in vivo, plasma D-dimer and fibrinogen as well as its degradation products were directly examined in three metastasis immune-deficient mouse models and in controls. Next, we gathered and analyzed the result of plasma D-dimer levels and CTCs numbers in 41 advanced primary gastric cancer (GC) patients. A follow-up study was conducted in these patients. Results: In three in vivo murine metastasis models, plasma D-dimer levels were extremely elevated in a hematogenous and intraperitoneal murine model of metastasis compared with a subcutaneous tumor model and the control group, supporting our previous hypothesis. While in 41 GC patients, the result displayed that plasma D-dimer levels were remarkably increased in patients with distant metastases, especially in visceral metastases patients. Additionally, linear association was shown between D-dimer level and CTCs numbers (R ² = 0.688, p < 0.001), additionally, plasma D-dimer represent a better survival predictor than CTCs. Conclusions: Plasma D-dimer is an essential accompaniment of CTCs in GC that is easy to measure and lower in cost, and can be used in the detection of hematogenous metastasis.