What is Cancer-Associated Thrombosis?
Patients with cancer frequently have a higher chance of developing blood clots, both in veins and in arteries. Venous thromboembolism (VTE), or blood clots occurring in veins, is one of the most common reasons for illness and death in people with cancer. The cause of this disease is linked to a state where the blood clots more easily than it should, due to an increased production of substances like tissue factor, which help in clot formation. A venous thromboembolism can sometimes be the first sign of hidden cancer, but it most often happens within six months of a cancer diagnosis.
What Causes Cancer-Associated Thrombosis?
Many things can lead to a higher possibility of blood clots in the arteries (arterial thromboembolism) and veins (venous thromboembolism) in cancer patients:
1. The tissue and structure of the tumor itself
2. Other health conditions the patient has, including being overweight and older in age
3. Treatments for cancer, like surgery and medical cancer therapy
Risk Factors and Frequency for Cancer-Associated Thrombosis
Cancer and blood clotting disorders like thrombosis have been linked since as far back as 1823. Research indicates cancer patients have a higher chance, up to 20%, of developing thrombosis. A study in the Netherlands involving 3220 participants aged 18 to 70 found cancer patients’ risk of venous thrombosis (a type of clot) to be seven times higher than regular folks. This risk was particularly high shortly after a cancer diagnosis and was especially seen in patients with blood cancers, lung cancer, gastrointestinal cancer, or advanced-stage cancers.
In another Minnesota-based study, cancer patients were found to have four times the usual risk of developing thrombosis, and this risk was even higher for cancer patients undergoing chemotherapy.
It’s not just venous thrombosis; cancer patients also face a higher risk of arterial thromboembolism (blood clots in arteries). In a retrospective study involving 279,719 pairs of cancer patients and their matched controls, findings showed higher rates of heart attacks and stroke in cancer patients (2.0% and 3.0%) compared to control patients (0.7% and 1.6%). Unfortunately, cancer patients who experience arterial thromboembolism also have a worse prognosis, with a three times higher risk of dying.
Signs and Symptoms of Cancer-Associated Thrombosis
Taking a detailed medical history and carrying out a complete physical examination is crucial. Blood clot events can happen in patients who are already known to have cancer, or they can be the first sign of the disease. Patients might show up with a condition called venous thromboembolism, which is deep vein thrombosis (a clot in a deep vein, often in the legs) or a pulmonary embolism (a sudden blockage in a lung artery). In rarer cases, the blood clot can occur in an artery causing an ischemic stroke (clot in the brain) or a heart attack.
Testing for Cancer-Associated Thrombosis
If someone has an unexpected blood clot in their veins (unprovoked venous thromboembolism) or arteries without any clear reasons (arterial thrombosis without identifiable cardiovascular risk factors), the doctor may suspect hidden cancer. At present, there’s not enough evidence to say that extensive testing to find hidden cancer would help reduce deaths related to cancer in patients with these types of unprovoked blood clots. However, it is important to have regular cancer screenings that are appropriate for your age.
Treatment Options for Cancer-Associated Thrombosis
Patients with active cancer have a higher risk of developing a dangerous condition called thromboembolism, in which blood clots form and can block blood vessels (veins or artery). It’s been found that preventative measures, known as thromboprophylaxis, can help reduce this risk. Research involving almost 12,000 patients concluded that thromboprophylaxis resulted in fewer cases of blood clots in cancer patients undergoing chemotherapy or surgery, without any notable increase in severe bleeding.
The National Comprehensive Cancer Network recommends using anticoagulation medications, which help prevent blood clots, in hospitalized cancer patients as a preventative measure. These medications include unfractionated heparin or low molecular weight heparin. If a patient is at risk of bleeding, has a low platelet count (thrombocytopenia), or has a tube inserted into their spinal space (an indwelling neuraxial catheter), mechanical preventative measures should be used instead of medication.
Research has also explored how long anticoagulation should be used in cancer patients who are hospitalized due to acute illnesses. It seems that using anticoagulation for a longer period doesn’t significantly reduce the risk of blood clots compared to a standard treatment duration, and in fact, it might double the risk of bleeding.
In terms of blood clot prevention in non-hospitalized patients, those who’ve had pelvic or abdominal cancer surgery might benefit from continuing the preventative measures up to four weeks post-surgery. For patients with a certain type of cancer called multiple myeloma who are taking medications that modulate the immune system, the use of aspirin or anticoagulation therapy is recommended.
If solid cancer patients are receiving chemotherapy and have a high Khorana score (a risk assessment for chemotherapy-associated blood clots), preventative anticoagulation therapy can decrease the incidence of blood clots in the lungs (pulmonary embolism).
Low molecular weight heparin (LMWH) is currently the preferred anticoagulation option used to manage cancer-associated thrombosis. Other treatment options include apixaban, rivaroxaban, edoxaban, fondaparinux, and warfarin. In some cases, patients with severe blood clots threatening to cause harm or loss of a limb can undergo thrombolytic therapy, which involves injecting medications to rapidly dissolve the clot. However, this therapy should be avoided in patients with brain tumors or metastasis, active bleeding, and a history of bleeding inside the skull.
For all these treatments, it’s important to constantly evaluate the benefits against the risks and to monitor for complications. In the presence of a blood clot in large, peripheral veins and if a patient cannot receive anticoagulation therapy, a device known as a retrievable vena cava filter can be inserted to prevent the clot from reaching the lungs. The device should be periodically reviewed for possible removal and a switch to anticoagulation therapy.
For patients with thrombosis in the superficial veins (the veins that are close to the surface of the body), the treatment will depend on whether the clot is related to a catheter or not. If it is, the catheter should be removed and anticoagulation might be considered if the clot starts to progress. For patients whose superficial vein thrombosis is not catheter-related, especially if it’s in the legs, at least six weeks of anticoagulation therapy is typically advised.
What else can Cancer-Associated Thrombosis be?
Cancer can sometimes lead to unexpected blood clotting, known as thromboembolic disease. According to a recent study which involved 245 patients with this type of disease, it was found that 4.1% of them had a hidden form of cancer. However, when dealing with unexpected cases of thromboembolic disease, it’s crucial for medical professionals to also consider other possible causes, such as:
- Thrombophilic disorders (conditions that increase the risk of blood clotting)
- Nephrotic syndrome (a kidney disorder causing your body to excrete too much protein in your urine)
- Antiphospholipid syndrome (an autoimmune disorder that can cause blood clots)
- Myeloproliferative neoplasms (blood cancers that cause excess production of red blood cells, white blood cells, or platelets)
- Severe liver disease
- Inflammatory bowel disease (chronic inflammation of all or part of your digestive tract)
What to expect with Cancer-Associated Thrombosis
Thrombosis, or blood clots, that occur in association with cancer can increase the risk of death for cancer patients. According to a study of 8 million Medicare patients who were admitted due to blood clots, the chances of dying within six months of hospital admission were 94% for cancer patients, as compared to 29% for patients without cancer.
Most of the deaths in patients with cancer-related thrombosis were due to arterial thrombosis, which is essentially blood clots in the arteries and can lead to heart attacks and strokes cutting off blood supply to vital organs. In a review of 4,466 patients, 9.2% of deaths were due to blood clot-related conditions. Of these, 5.6% involved arterial thrombosis.
Possible Complications When Diagnosed with Cancer-Associated Thrombosis
In people with cancer, having a blood clot can lead to severe issues. These include a higher chance of getting another blood clot, bleeding problems while on blood-thinning medication, more frequent hospital stays, and higher death rates.
Key Risk Factors:
- Higher chances of another blood clot
- Bleeding problems during blood-thinning treatment
- Increased hospital visits
- Higher risk of death
Preventing Cancer-Associated Thrombosis
Patients with active cancer are more likely to develop blood clots in their veins and arteries. It’s crucial for these patients to understand that they have a higher risk of developing blood clots related to their cancer. They should be aware of possible signs and symptoms, like swelling in one leg, a feeling of your heart beating rapidly, pain in the chest, difficulty breathing, and signs of a stroke.
For people who don’t have cancer but have experienced unexpected blood clots, it is very important to get regular cancer screenings suitable for your age. This is to check for any hidden cancers that might have gone unnoticed.
