Praxis Medical Insights

Est. 2024 • Clinical Guidelines Distilled

Made possible by volunteer editors from the University of Calgary & University of Alberta

Last Updated: 10/9/2025

Chemotherapy-Associated Thrombosis

Introduction to Risk

  • Cancer patients receiving chemotherapy have a 7-fold increased risk of pulmonary embolism (PE) and venous thromboembolism (VTE) compared to those not receiving chemotherapy, according to the European Society for Medical Oncology (ESMO) 1, 2
  • The American Society of Clinical Oncology (ASCO) and ESMO guidelines demonstrate a clear and substantial risk increase, with cancer patients on chemotherapy having a 6.5-fold increased risk of VTE compared to the general population 3

Mechanisms of Chemotherapy-Induced Thrombosis

  • The European Society for Medical Oncology (ESMO) identifies four distinct mechanisms by which cytotoxic chemotherapy increases PE risk, including acute vascular endothelial damage, chronic endothelial injury, depletion of natural anticoagulants, and platelet activation 4, 5, 1, 6

High-Risk Chemotherapy Regimens

  • Bevacizumab with chemotherapy increases VTE by 33%, with an overall VTE incidence of 11.9% (any grade) and 6.3% (high-grade), as reported by the American Society of Clinical Oncology (ASCO) 4, 5, 7
  • Thalidomide plus doxorubicin in multiple myeloma carries up to a 34% VTE rate, according to the International Myeloma Society 4, 5
  • Lenalidomide with high-dose dexamethasone in relapsed myeloma shows similarly elevated rates, as reported by the European Society for Medical Oncology (ESMO) 4, 5

Risk Stratification for Chemotherapy Patients

  • The ESMO guidelines provide a validated predictive model for chemotherapy-associated VTE, including cancer site risk scores, laboratory risk factors, and patient factors, such as BMI ≥35 kg/m² 4, 6
  • The model categorizes patients into low-risk (score 0), intermediate-risk (score 1-2), and high-risk (score ≥3) groups, with corresponding VTE rates of 0.5%, 2%, and 7%, respectively 4, 6, 1

Clinical Impact and Mortality

  • VTE increases mortality risk 3-fold in cancer patients, according to the European Heart Journal 8, 7
  • The 30-day risk of death, shock, or recurrent PE triples when cancer patients develop VTE, as reported by the European Heart Journal 8
  • The 3-month all-cause mortality reaches 26.4% in cancer patients with VTE versus 4.1% without, according to the European Heart Journal 8

REFERENCES

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