Evidence from broader cancer populations suggests that pharmacological thromboprophylaxis with direct oral anticoagulants or low-molecular-weight heparin approximately halves the risk of symptomatic VTE but may double the risk of major bleeding. In patients with MIBC receiving neoadjuvant chemotherapy, a recent meta-analysis suggests that the risk of VTE during NAC for MIBC is around 8%, rising to 17% in studies with post-NAC scanning, while the risk of bleeding may be low. However, these estimates remain uncertain, and the overall net benefit of routine pharmacological thromboprophylaxis in this specific setting remains unclear.
No published randomized trial has examined pharmacological thromboprophylaxis in patients with MIBC undergoing NAC. Leading American (ASCO) and European (ESMO) guidelines acknowledge the issue but give no clear guidance. We therefore conducted an international cross-sectional survey of oncologists and urologists who administer NAC for MIBC in the United Kingdom, Finland, Sweden, Denmark, and Iceland.
The survey assessed clinician characteristics, current use of pharmacological thromboprophylaxis, preferred agents, and reasons for withholding prophylaxis. We received 46 responses (44 oncologists and 2 urologists) from 67 invited clinicians (response rate 69%), and the completion rate was very high (98% completed every survey question). The median age of respondents was 49 years, and 46% were women. The median time in specialist practice was 12 years, and respondents reported treating a median of 15 MIBC NAC cases per year.
We found that pharmacological thromboprophylaxis is not routinely used in these patients. Overall, 20/46 (43%) of respondents reported prescribing pharmacological thromboprophylaxis during NAC. However, most clinicians reported prescribing it to fewer than 10% of patients (33/46, 72%). Only two respondents reported prescribing thromboprophylaxis for at least 90% of patients they treat. Among clinicians who reported using prophylaxis, low-molecular-weight heparin was the most commonly selected agent, followed by direct oral anticoagulants.
The main reason for not initiating pharmacological thromboprophylaxis was insufficient evidence of benefit, reported by 57% of respondents. Concerns about bleeding were the second most frequent reason, reported by 28%. Fewer respondents cited a perceived low risk of thrombosis, inconvenience for patients, or lack of guideline recommendations.
In summary, we performed an international survey and achieved a high response rate. We found that clinicians rarely prescribe thromboprophylaxis for patients receiving NAC for MIBC. The dominant reasons for withholding therapy were insufficient evidence of benefit and the belief that the risk of bleeding outweighs the risk of thrombosis in these patients. These findings highlight substantial clinical uncertainty and a lack of evidence-based consensus regarding thromboprophylaxis during neoadjuvant chemotherapy for MIBC. They also reinforce the need for randomized evidence to determine whether thromboprophylaxis improves patient-important outcomes in this population.
Written by:
- Alex L. E. Halme, Faculty of Medicine, University of Helsinki, Helsinki, Finland
- Kari A. O. Tikkinen, Department of Urology, University of Helsinki and Helsinki University Hospital, Helsinki, Finland; Department of Public Health, Faculty of Medicine, University of Helsinki, Helsinki, Finland; Department of Health Research Methods, Evidence and Impact, McMaster University, Hamilton, Ontario, Canada