Cancer-related VTE

    Cancer-associated VTE is not rare; it is a major complication of cancer and its treatment. VTE in cancer can be linked to known factors like surgery or hospitalization, as well as cancer-driven due to the ongoing risks because of the disease itself.

    vte_diagram

    What is VTE?

    Venous thromboembolism (VTE) is a common and preventable condition where a blood clot forms in a vein, usually in the legs but sometimes in the arms.

    VTE includes two main conditions: 

    • Deep vein thrombosis (DVT): a clot in the leg, thigh, or pelvis (most common)
    • Pulmonary embolism (PE): when a clot breaks loose and travels to the lungs (can be life-threatening)

    VTE is often underdiagnosed but serious, especially in people with cancer. 

    Top Ten Questions to Ask Your Doctor: When You’re Newly Diagnosed with Colorectal Cancer

    Why VTE Matters in Cancer

    Cancer-associated VTE is not rare; it is a major complication of cancer and its treatment. VTE in cancer can be linked to known factors like surgery or hospitalization, as well as cancer-driven due to the ongoing risks because of the disease itself.

    • 20–30% of all first VTE events are cancer-related
    • Cancer patients have a 4 – 7x higher risk of developing VTE compared to people without cancer
    • VTE is one of the leading causes of death in cancer patients outside of cancer progression itself
    • Colorectal cancer is considered moderate to high risk for cancer-associated thrombosis compared to other tumor types
    Risks and complications

    When Risk is Highest

    VTE risk is not constant. It increases during specific periods:

    • Early after cancer diagnosis
    • During chemotherapy
    • After surgery (risk is higher post-operatively in cancer patients)
    • Within the first 3 months of starting chemotherapy, when nearly half of VTE events may occur (approximately 47%)
    • After discharge, due to the challenges during the transition of care

    This timing is critical for education and prevention planning.

    Why Colorectal Cancer Patients Are at Increased Risk

    Cancer creates a pro-thrombotic (hypercoagulable) state, a condition where blood has an increased tendency to form clots, leading to a higher risk of venous or arterial thrombosis. In CRC specifically:

    khorana_score_VTE

    Prevention in CRC Patients

    Surgical patients

    • Standard of care: postoperative anticoagulant prophylaxis
    • Extended prophylaxis (up to 4 weeks) may be recommended after major abdominal cancer surgery

    Ambulatory patients on chemotherapy

    • Clinicians may use risk assessment tools such as the Khorana score to estimate clot risk in patients undergoing chemotherapy
    • High-risk patients may be offered preventive anticoagulation (blood thinners)

    Not all CRC patients automatically receive prophylaxis. This is risk-based.

    Signs and Symptoms

    Many patients don’t realize these symptoms are related to cancer risk and should feel empowered to discuss risk, options, and when to seek urgent care.

    Possible DVT symptoms

    • Leg swelling (usually one-sided)
    • Pain or tenderness
    • Warmth
    • Redness or discoloration

    Possible Pulmonary Embolism (PE) symptoms (medical emergency)

    • Sudden shortness of breath
    • Chest pain (worse with breathing)
    • Rapid heart rate
    • Lightheadedness

    man holding pink pills

    Treatment of Cancer-Associated VTE

    Historically:

    • Low molecular weight heparin (LMWH) was standard

    Currently:

    • Direct oral anticoagulants (DOACs) (e.g., apixaban, rivaroxaban, edoxaban) are now commonly used
    • Treatment duration is typically at least 3–6 months, often longer if cancer is active

    Important nuance for CRC:

    • GI cancers may have a slightly higher bleeding risk with some anticoagulant medications
    • Treatment choice balances clot risk vs bleeding risk

    Questions to Ask Your Doctor About VTE

    VTE Resource

    If you have colorectal cancer, it’s important to talk to your care team about your risk for blood clots. Use this guide to learn key information about VTE, why it matters, and signs and symptoms to be aware of.

    Download Resource

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