Benefit of prophylactic anticoagulation before and during first-line chemotherapy on patients with metastatic germ cell tumors.

Background: Recent trials randomising patients (pts) receiving systemic cancer therapy showed that prophylactic anticoagulation (PAK) halves the risk of venous thromboembolic events (VTE) and doubles the risk of bleeding (Khorana et al. & Carrier et al., both NEJM 2019). In pts with metastatic germ cell tumors (mGCT) VTE is a frequent complication but it remains unclear whether PAK should be recommended because the number of mGCT pts in those trials was small. We aimed to determine the risk of VTE before, during and after chemotherapy and in mGCT pts without and with risk factors for VTE (retroperitoneal lymph nodes, Khorana score, venous access device) and to calculate the number needed to treat (NNT) and number needed to harm (NNH) of PAK. Method(s): This retrospective analysis included mGCT pts treated with first-line platinum-based chemotherapy. We excluded patients who received PAK, with a known history of coagulopathy or VTE and extracted data about VTE and bleeding events. Cumulative VTE incidence was calculate for patients without and with increasing number of known risk factors for VTEs. NNT and NNH were calculated by assuming similar hazard ratios (HR) to reduce VTEs and increase bleeding as previously published (HR 0.66 and 1.96, Khorana et al., NEJM 2019). Result(s): Out of 1039 pts, 132 (13%) presented with VTE, 6 (1%) with bleeding. One patients died of VTE and 1 because of bleeding. Patients without any VTE risk factors experience VTE in 20/347 (5%) which translated into a NNT of 55 compared to the NNH of 84 respectively. Before start of chemotherapy 52 (5%) pts (NNT=60) presented with VTE of which 22 were reported symptomatic 21 asymptomatic/incidentally detected VTE on staging scans (9 unknowns). During chemotherapy 79 (8%) pts (NNT=40) were diagnosed with VTE whereas 19 (2%) pts (NNT=162) were diagnosed with VTE after chemotherapy. Conclusion(s): Our analysis revealed that even mGCT patients without risk factors for VTE show a relevant cumulative V