This study found that the levels of sP-selectin and VWF in cancer patients with DVT pre-chemotherapy and post-chemotherapy were higher than patients without DVT. Furthermore, the levels of sP-selectin and VWF were getting higher after chemotherapy. In DVT cancer patients, the levels of sP-selectin and VWF were significantly higher than patients without DVT in both pre-chemotherapy and post-chemotherapy (p = 0.041; p = 0.000 and p = 0,001; p = 0,002, respectively).
In the patients with DVT, the levels of ADAMTS13 pre-chemotherapy and post-chemotherapy were lower than patients without DVT. The levels of ADAMTS13 were significantly lower than patients without DVT in both pre-chemotherapy and post-chemotherapy (p = 0.007 and p = 0.001, respectively).
It is known that sP selectin and VWF are stored in platelets alpha granules and WPB bodies endothelial cells.12,14 The study conducted by Payne H et al. on mice showed that endothelial activation and WPB exocytosis were immunity mechanism which initiated DVT. In this process, WPB fused with plasma membrane and released its constituents such as VWF and sP-selectin, in membrane, which allowed cell recruitments. It corresponded with the increasing levels of sP-selectin and VWF in the patients with DVT.18
Soluble P-selectin and VWF levels in the cancer patients with DVT, which were already high before chemotherapy and increased higher after chemotherapy showed that immune systems and inflammations, played significant roles in DVT pathogenesis.1 Cancers and chemotherapy treatments can cause inflammatory conditions.19 In cancers, there are inflammatory stimulates in the tumor microenvironment.20,21 Inflammatory stimulates in cancers and chemotherapy activate intracellular signal pathways which activate the production of inflammatory mediators.22,23 Blood vessel invasions by cancer cells, diagnostic and therapeutic interventions, such as central venous catheter insertion, also cause injuries in cancer patients’ blood vessels. This leads to endothelial cells damage which prompts endothelial cells activation resulting in inflammatory responses.19
Systemic chemotherapy may cause injuries on blood vessel walls due to its direct toxic effect on endothelial cells which prompts endothelial cell activation. The increasing activation of endothelial cells is considered as one of the causes of increasing hemostatic activation.4,5 Biochemically, chemotherapy-induced VECA is indicated by increasing endothelial cells in circulation, VWF in plasma and endothelial cell activation markers such as VCAM-1, sP-selectin and E-selectin.5,6 The rising endothelial activities as a result of inflammatory induce various changes in endothelial cells and leukocytes and platelets which encourage procoagulant and prothrombotic surfaces in blood vessel walls that increase the risk of DVT.6,24
The adhesion process of leukocytes to blood vessel endothelial cell is a feature of inflammatory proces.6 There are leukocyte rolling, adhesion, and movement to the injured spots controlled by selectin, integrin, and other adhesive molecules. Some adhesive molecules such as P-selectin, involved in inflammation, contribute in thrombosis.15 The interaction between P-selectin and its main receptor in leukocytes, P-selectin glycoprotein ligand 1 (PSGL-1), causes neutrophil and macrophage recruitment; together with other mediators, they induce leucocytes to produce procoagulant microparticles. Subsequently, P-selectin prompts rising TF expressions in monocytes and mediates TF transfer to platelets. Tissue factor is the main initiator of in vivo coagulant, causing the activation of coagulant cascade extrinsic pathways.13 The study conducted by Ay et al. has showed that an elevated levels of sPselectin is a useful parameter to identify patients who are at risk of thrombotic events, showing an odds ratio of 2.6 for patients with serum levels of sPselectin > 53.1 ng/dl after adjusted for age, sex, surgery, chemotherapy and radiotherapy.25
Von Willebrand factor has a role in both primary and secondary hemostasis. This glycoprotein acts as a carrier for factor VIII and a platelet adhesion mediator to endothelial cells.16 Von Willebrand factor is an adhesive protein capable of attaching to tumor cells and platelets, which can cause microthrombi formations. Platelet-tumor cell aggregation also facilitate the metastasis process by making it easier for tumor cells to adhere and migrate through vessel walls.26 The previous study has shown that the numbers will increase in cancer patients with DVT and are related to cancer stage and metastasis. The increasing VWF antigen and the decreasing VWF-cleaving protease will prompt thrombogenesis in cancer patients.17 High VWF levels were significantly associated with the risk of developing DVT in cancer patients.27
The rise of VWF in circulation causes increasing ADAMTS13 activities, which results in decreasing levels of ADAMTS13. Mechanistically, this association is hypothesized that DVT related to cancers can be based on platelet aggregations mediated by VWF. Bauer et al. have recently showed that melanoma cells could activate vascular endothelial cells and push them to release ULVWF followed by platelets aggregation in vitro. They further explained that a combination of VWF release and decreased ADAMTS13 in tumor tissues tend to prompt procoagulant environment.28 The decrease in ADAMTS-13 activities, which regulate size and, therefore, affect VWF cleansing from circulation, may result in a rise in plasma VWF. Although the mechanism prompting a decrease in plasma ADAMTS-13 in cancer patients has not been fully understood, various oncogenes have been found to regulate the expression of extracellular proteinases, including matrix-degrading metalloproteinases, which can directly disrupt ADAMTS13 activities.26
The result of this study also showed that the cut-off points of sP-selectin and VWF levels were high both pre-chemotherapy and post-chemotherapy and the low levels of ADAMTS13 pre-chemotherapy and post-chemotherapy posed high relative risk for DVT incidence. The levels of sP-selectin, VWF and ADAMTS13 pre-chemotherapy with cut-off point > 106.7 ng/mL, > 2.99 U/mL and < 0,80 U/mL, respectively had RR for DVT incidence being 16 (95% CI 2,06-124,25, p = 0,001); 36 (95% CI 5,21–248,65, p = 0,000) and 10,5 (95% CI 1,31–84,28, p = 0,015) respectively, whereas the levels of sP-selectin, VWF and ADAMTS13 during post-chemotherapy with cut-off point > 111.7 ng/mL, > 3,06 U/mL and < 0,49 U/mL, respectively, had RR for DVT incidence being 8.7 (95% CI 1,01–74,39, p = 0,045); 20,4 (95% CI 2,60–159,94, p = 0,004) and 26,25 (95% CI 3,50–196,48, p = 0,002), respectively.
The data above indicated that the cut-off points of sP-selectin, VWF, and ADAMTS13 levels both pre-chemotherapy and post-chemotherapy could be used to predict the incidence of DVT in the cancer patients undergoing chemotherapy. Multiple logistic regression analysis is performed to determine the strongest biomarker as a predictor of DVT incidence pre- and post-chemotherapy.
Multiple logistic regression analysis showed that VWF levels pre-chemotherapy was the strongest biomarker as a predictor of DVT incidence pre-chemoterapy. Cancer patients whose initially have VWF levels > 2.99 U/mL will have 11-fold increased risk of developing DVT (RR 11,1;95% CI 1.95–62.74, p = 0.007) independently to other coagulation marker such as sP-selectin and ADAMTS13. The data above indicated that the cut-off points of VWF levels > 2.99 U/mL effectively predict the incidence of DVT in cancer patients undergoing chemotherapy.
Deep vein thrombosis has long been considered as a blood clotting disorder. The new understanding of DVT mechanism with some evidence and research data above shows the important role of immune systems and inflammations in the pathogenesis of DVT. Deep vein thrombosis is a process related to immunity and inflammation, not just the coagulation process that causes thrombosis. Local endothelial activations and the release of WPB present in endothelial cells have a very important role in initiating DVT. In addition to vascular systems, the immune system is emerging as a pivotal player in the pathophysiology of DVT.1,29
The paradigm above opens the way to new thoughts on studies about new potential thromboprophylaxis strategies, or suggests a role for anti-inflammatory, which could be used for DVT prevention with a lower risk of bleeding complications than conventional therapeutic approaches.1,29
The limitation of this study is that sP-Selectin, VWF, ADAMTS13 and color duplex sonography serial examinations were not conducted monthly. They can be used to see the changes in the levels of sP-selectin, VWF and ADAMTS13 every chemotherapy cycle, so that the changes in biomarker levels and the incidence of DVT can be observed regularly. It will allow us to see the changes in biomarker levels affecting DVT incidence more accurately.