Cancer-Associated VTE

Definition

Cancer-associated venous thromboembolism (VTE) — encompassing DVT, pulmonary embolism, superficial thrombophlebitis, catheter-associated thrombosis, and iliocaval thrombosis — is the most common cardiovascular complication of malignancy. Cancer itself acts as a pro-thrombotic state through multiple mechanisms (activation of the coagulation cascade, endothelial injury, platelet activation, impaired fibrinolysis), and many cancer therapies amplify this risk further.

Key Concepts

Epidemiology

• Cancer increases VTE risk 7–8-fold vs. the general population. (sources/cardio-oncology-vascular-metabolic-aha-2019, rating: very high)
• Hematological malignancies: 28× increased odds of VTE; lung and GI tumors: >20×. (sources/cardio-oncology-vascular-metabolic-aha-2019)
• Annual incidence: 0.5% in cancer vs. 0.1% in general population; cancer accounts for ~20% of total VTE burden. (sources/cardio-oncology-vascular-metabolic-aha-2019)
• Risk highest in first year after cancer diagnosis (15-fold); increases with metastatic spread (2-year cumulative incidence rises from localized → regional → remote disease). (sources/cardio-oncology-vascular-metabolic-aha-2019)
• Despite stable background VTE rates, cancer-associated VTE incidence is increasing over time. (sources/cardio-oncology-vascular-metabolic-aha-2019)
• Cancer-VTE clot burden is higher: bilateral lower limb DVT, iliocaval thrombosis, upper limb DVT all more common vs. non-cancer VTE. (sources/cardio-oncology-vascular-metabolic-aha-2019)

Prognosis

• VTE in cancer is a poor prognostic sign: mortality 5–6× higher vs. non-cancer VTE. (sources/cardio-oncology-vascular-metabolic-aha-2019)
• Within cancer-only populations, VTE increases mortality 1.6–4.2-fold. (sources/cardio-oncology-vascular-metabolic-aha-2019)
• Patients with cancer-associated VTE have increased bleeding risk AND increased VTE recurrence risk. (sources/cardio-oncology-vascular-metabolic-aha-2019)

Recurrence Risk — Ottawa Score

• Ottawa Score predicts recurrent VTE in cancer-associated thrombosis: (sources/cardio-oncology-vascular-metabolic-aha-2019, rating: very high)

• Score ≤0 = Low risk (<4.5% recurrence); Score ≥1 = High risk (~19% recurrence)

• Performance: 100% sensitivity, 98.1% NPV, negative likelihood ratio 0.16

• Validated in 2 RCTs of anticoagulation in cancer-associated VTE

• VTE recurrence rate: ~21% at 1 year in cancer vs. 7% in non-cancer VTE; relative risk 2.4× for DVT and 2.0× for PE recurrence (RIETE registry, n~19,000). (sources/cardio-oncology-vascular-metabolic-aha-2019)

Anticoagulation Strategy

Duration

• Extended/indefinite anticoagulation (no scheduled stop date) recommended even with high bleeding risk — ACCP guidelines (because recurrence risk is consistently elevated). (sources/cardio-oncology-vascular-metabolic-aha-2019)
• No recommendation for routine VTE prophylaxis in cancer outpatients, except multiple myeloma patients on thalidomide/lenalidomide-based regimens (risk-stratified prophylaxis required).

Drug Choice

• LMWH preferred over VKA — two pivotal trials showed superiority for recurrent VTE prevention: (sources/cardio-oncology-vascular-metabolic-aha-2019)
  • Dalteparin (CLOT trial): superior to warfarin for recurrent VTE
  • Enoxaparin (LITE trial): superior to warfarin for recurrent VTE
  • Tinzaparin: trended toward benefit, did not reach statistical significance
  • Limitations of LMWH: cost, injections, no easy reversal agent

Emerging DOAC Evidence (2019 Data)

• Edoxaban vs. dalteparin (n=1,050; 6–12 months): Primary outcome (recurrent VTE or major bleeding) 12.8% vs. 13.5% — non-inferior (P=0.006 for noninferiority). (sources/cardio-oncology-vascular-metabolic-aha-2019)
• Rivaroxaban vs. dalteparin (pilot): VTE recurrence HR 0.43 (CI 0.19–0.99) — fewer recurrences; but clinically relevant non-major bleeding HR 3.76 (CI 1.63–8.69) — more bleeding. (sources/cardio-oncology-vascular-metabolic-aha-2019)
• Apixaban vs. dalteparin (abstract presentation): VTE recurrence 3.4% vs. 14.1% (HR 0.26, CI 0.09–0.80; P=0.018) with superior QoL and very low bleeding rates. (sources/cardio-oncology-vascular-metabolic-aha-2019)
• Conclusion (2019 view): DOACs likely to become standard for cancer-associated VTE, but caveats apply — renal/liver dysfunction effects on dosing, drug-drug interactions (P-glycoprotein and CYP3A4 substrates), reversibility of anticoagulation

Immunomodulator (Thalidomide/Lenalidomide) VTE Prophylaxis

• 3-tier risk stratification for thromboprophylaxis: (sources/cardio-oncology-vascular-metabolic-aha-2019)
  • Low risk (single-agent thalidomide/analog, no additional risk factors): no prophylaxis required (<5%)
  • Standard risk (no/1 risk factor, not on multiagent chemo or high-dose dexamethasone): aspirin 81 mg/day (up to 20% risk)
  • High risk (≥2 risk factors OR multiagent chemo OR high-dose dexamethasone): LMWH or warfarin

Drug-Related VTE Risk

• Bevacizumab (VEGF-A antibody): Highest VTE incidence among VEGF inhibitors — ~12% of patients; nearly half are high-grade. (sources/cardio-oncology-vascular-metabolic-aha-2019)
• VEGF receptor TKIs (sunitinib, sorafenib, etc.): VTE incidence 2–6%. (sources/cardio-oncology-vascular-metabolic-aha-2019)
• IMiDs (thalidomide, lenalidomide): Predominantly venous events; risk amplified by concomitant multiagent chemotherapy/dexamethasone. (sources/cardio-oncology-vascular-metabolic-aha-2019)
• BCR-ABL TKIs (ponatinib, nilotinib): Arterial ischaemic events dominate; VTE also described. (sources/cardio-oncology-vascular-metabolic-aha-2019)

Contradictions / Open Questions

• DOAC data at time of this 2019 statement were from pilot studies and abstract presentations — prospective DOAC cancer-VTE RCTs were pending; subsequent data (Caravaggio, SELECT-D) have since supported DOAC use, but concerns about bleeding with GI/GU cancers persist.
• Ottawa Score validated in VTE-treatment RCTs but not in broader oncology populations.
• No validated cancer-specific bleeding score exists; HAS-BLED underperforms in cancer patients (does not capture thrombocytopenia or intracranial metastases). See concepts/Cancer-Therapy-Related-CV-Toxicity.
• Routine VTE prophylaxis in cancer outpatients is not recommended, but selected high-risk patients (Khorana score ≥2) may benefit — guidelines evolving. (sources/cardio-oncology-vascular-metabolic-aha-2019)

Connections

• Related to concepts/Cancer-Therapy-Related-CV-Toxicity
• Related to concepts/Cardio-Oncology
• Related to entities/Pulmonary-Hypertension
• Related to sources/cardio-oncology-vascular-metabolic-aha-2019

Sources

• sources/cardio-oncology-vascular-metabolic-aha-2019