The aim of the present study was to evaluate the changes in hypercoagulable state after radical prostatectomy using thrombin generation assay. This measurement provides new metrics of hemorrhage control and vascular occlusion, and allows sufficient evaluation of an individual’s hemostatic competence and response to anticoagulant therapy 
The results of our thrombin generation tests showed remarkable changes following radical prostatectomy. An even more significant difference in thrombin generation was found between the preoperative patient group and healthy control group. When compared to the controls, baseline thrombin generation and AUC were higher in the cancer patients which finding could be due to a variety of causes such as the presence of tumor cells, of microparticles and tissue factor 
. Tissue factor and microparticles highly enhance procoagulant activity and thus influence the thrombin generation parameters 
. The difference of the TGA parameters between the controls and the preoperative values of the study population revealed increased procoagulant activity, which were further stimulated by the surgical intervention. The effect of the operation disappeared to the end of the first postoperative month. This supports the findings of other studies that the high-risk period after radical pelvic surgery ends before the first month 
. The difference compared to the control group disappeared only by the 10 month check. The elevated baseline TG levels indicate the possible malignant procogulant activity of the prostate cancer, which is amplified by the surgical intervention.
Butenas et al confirmed that prothrombin and AT levels are dominant factors that influence thrombin generation when a synthetic “plasma” system was supplemented with factors II, X, XI, IX, VII, VIII and V, proteins C and S, AT and tissue factor pathway inhibitor 
. A 50% decrease of AT increased thrombin production from 104% to 196%. However, as the decrease of AT in our samples was less than 10% and all levels remained within the reference range (80–120%), this cannot explain the remarkable increase in the thrombin generation seen in our study.
Changes in white blood cell counts reveal the acute immunological reaction to the tissue trauma, with an early compensation. Platelet count and conventional clotting tests varied somewhat, but all remained within the reference ranges, similar to what was observed after transurethral resection of benign prostatic hyperplasia 
. Possible LMWH inhibitory actions on procoagulant factors can be excluded as at the moment of blood sampling, the levels in all samples were below the detection limit when measuring inhibition of FXa, consequently LMWH could not have influenced the result by decreasing procoagulant activity.
According to the correlation analysis of the FNG levels, conventional clotting times and TGA parameters we found that increased procoagulant activity is more readily detected when using the TGA, than by measuring changes in PT, APTT and TT levels. Elevated basic d dimer level was similar to published results 
. Fibrinogen-levels did show a slower response to tissue trauma, than d dimer and peak thrombin. Since we did not find a correlation between fibrinogen and peak thrombin generation, although fibrinogen influences thrombin generation 
, we conclude that in this altered balance of hemostasis as seen in the patients, it has a lesser contributing effect to the rise in peak thrombin levels or other TGA parameters.
Patients’ data were further analyzed for correlation between different clinical parameters and peak thrombin levels. Pathological tumor stage (pT) or additional lymphadenectomy was not significantly linked to TGA results. However, longer narcosis was observed to correlate with increased peak thrombin levels in the first postoperative sample. Baseline peak thrombin levels in plasma of patients with elevated body mass index (BMI>25) were similar to the normal BMI patients, but here a significant difference was seen on the sixth postoperative day. Beijers et al investigated the association between body composition and thrombin generation in plasma of 586 individuals and found an association with higher levels of thrombin generation in elderly women but not in men 
. We hypothesise that body shape (characterized by BMI) may have a latent effect on procoagulant activity as BMI level caused difference only on the 6th
postoperative day but this statement needs further evaluation.
Limitations of our study are (i) the relatively low number of cases with as a consequence that the probability of having clinical signs of thrombotic events during the follow-up was limited; (ii) two of the patients were administered irradiation and hormone therapy fro the 6th postoperative week; (iii) not all the data series showed Gaussian distribution, which decreased the statistical power; and (iv) there are other specific laboratory tests evaluating procoagulant activity, which were not evaluated in our study.
In conclusion, our study contributed to the knowledge of the pathophysiology of the hypercoagulable state of prostate cancer patients undergoing major pelvic surgery. Recent studies provided evidence that measurement of thrombin generation identifies patients at risk of venous thromboembolism 
, It’s well known fact that surgical therapy of pelvic malignancies mean an additional risk of venous thromboembolism due to the nature of the intervention and the disease, but the stage of hypercoagulability during the postoperative period of radical prostatectomy has not been demonstrated yet. The goal of our present study was to evaluate this level with the use of a test which usefulness was proven by other studies. Although our case number was low to reach statistical probability for clinical thrombotic events, our results and recent articles present the power of thrombin generation test to detect such a high increase of the hypercoagulability, which indicate the risk of thrombotic events as shown in large studies 
Factors influencing thrombotic risk are still not well defined but our results suggest that increased narcosis and BMI may contribute to procoagulant activity in the postoperative period, but this statement needs further assessment.
Our study together with recently published papers assessing risk factors for arterial or venous thromboembolism suggests the need for individual anticoagulant and antiplatelet management plan likely to achieve a low incidence of thrombosis and prevent bleeding. 
. To reach this goal, multidisciplinary approach is desirable.
Further evaluation of the hypercoagulable state in the postoperative period would lead urologists to an international and well supported consensus where e.g. anticoagulant treatment is considered for the first month only in order to provide a better clinical outcome.