American Society of Hirudotherapy

Clinical implications of incidental venous thromboembolism in cancer patients

Randomized controlled trial published in The European respiratory journal (2020)

Last Updated: June 18, 2026Reviewed by: ASH Editorial Board
Research article — evidence reviewArticle reference
Evidence: Randomized controlled trialClinical TrialsMulder FI et al. · The European respiratory journal, 2020

Abstract

INTRODUCTION: In cancer patients, current guidance suggests similar treatment for incidental and symptomatic venous thromboembolism (VTE), mainly based on retrospective data. We aimed to evaluate anticoagulant therapy in cancer patients with incidental and symptomatic VTE. METHODS: The Hokusai VTE Cancer Study was a randomised controlled trial comparing edoxaban with dalteparin for cancer-associated VTE. The primary outcome was the composite of first recurrent VTE or major bleeding. Secondary outcomes included major bleeding, recurrent VTE and mortality. Outcomes in patients with incidental and symptomatic VTE were evaluated during the 12-month study period. RESULTS: 331 patients with incidental VTE and 679 patients with symptomatic VTE were enrolled, of whom the index event was confirmed by an independent radiologist. Median durations of anticoagulant treatment were 195 and 189 days, respectively. In patients with incidental VTE, the primary outcome occurred in 12.7% of patients, major bleeding in 6.6% of patients and recurrent VTE in 7.9% of patients. Out of the 26 VTE recurrences in patients with incidental VTE, five (31%) were incidental, seven (44%) were symptomatic and four (25%) were deaths for which pulmonary embolism could not be ruled out. In patients with symptomatic VTE, the primary outcome occurred in 13.8% of patients, major bleeding in 4.9% of patients and recurrent VTE in 10.9% of patients. All-cause mortality was similar in both groups. CONCLUSION: Clinical adverse outcomes are substantial in both cancer patients with incidental and symptomatic VTE, supporting current guideline recommendations that suggest treating incidental VTE in the same manner as symptomatic VTE.

Abstract sourced from PubMed (NCBI) for the cited record. See the original publication for the authoritative version.

Publication typeJournal ArticleRandomized Controlled TrialResearch Support, Non-U.S. Gov't
Indexed MeSH termsAnticoagulantsDalteparinHumansNeoplasm Recurrence, LocalRetrospective StudiesVenous Thromboembolism

Summary

In cancer patients, current guidance suggests similar treatment for incidental and symptomatic venous thromboembolism (VTE), mainly based on retrospective data. We aimed to evaluate anticoagulant therapy in cancer patients with incidental and symptomatic VTE.

Why This Matters for Hirudotherapy

Drawing on the randomized Hokusai VTE Cancer trial (edoxaban vs dalteparin), this analysis compared 331 cancer patients with incidental VTE and 679 with symptomatic VTE, finding substantial adverse outcomes in both groups (composite recurrent VTE or major bleeding 12.7% vs 13.8%) and supporting guideline advice to treat incidental VTE like symptomatic VTE. For ASH this maps to the cancer-associated-thrombosis problem where the bleeding-versus-clotting balance is especially delicate -- the same balance that makes mechanistically distinct, leech-derived anticoagulant peptides a continuing drug-discovery interest. Honest caveat: although derived from RCT data, this is a secondary subgroup analysis comparing two pharmaceutical anticoagulants; it involves no leeches, makes no hirudotherapy claim, and cannot be presented as evidence for leech-based treatment.

Citation

Clinical implications of incidental venous thromboembolism in cancer patients.

Mulder FI et al. · The European respiratory journal, 2020

Added to ASH library: May 28, 2026 · Site last updated: June 18, 2026

This website provides educational information and does not constitute medical advice, diagnosis, or treatment recommendations. Medicinal leech therapy carries clinically meaningful risks and should be performed only by qualified clinicians under institutionally approved protocols. FDA 510(k) clearance for medicinal leeches is limited to specific indications; investigational and off-label discussions are labeled accordingly. For patient-specific guidance, consult a qualified healthcare provider.