Cancer and stroke share a complex connection. A cancer diagnosis can substantially increase an individual’s likelihood of experiencing a stroke. This relationship involves various biological pathways and treatment-related factors that influence the body’s vascular system.
The Link Between Cancer and Stroke
Cancer is a recognized risk factor for stroke. Patients with cancer face an elevated probability of experiencing a stroke compared to the general population. This increased susceptibility is a known complication of malignancy, influencing patient care and monitoring. Some studies indicate that up to 13% of ischemic stroke patients have a known history of cancer.
How Cancer Can Lead to Stroke
Hypercoagulability
Cancer can significantly alter the body’s blood clotting mechanisms, leading to a state known as hypercoagulability. Tumor cells often produce and secrete procoagulant substances, such as tissue factor (TF), which directly activate the coagulation cascade. This activation makes the blood more prone to forming clots within vessels. Inflammation associated with cancer also contributes to this prothrombotic environment by triggering host cells, like monocytes and platelets, to express more tissue factor and become activated.
The interaction between tumor cells and blood components, including monocytes, neutrophils, and platelets, promotes clot formation. This systemic activation of blood coagulation is often detectable through elevated levels of circulating thrombotic biomarkers, such as D-dimer.
Direct Tumor Effects
Tumors can directly interfere with blood flow, potentially leading to a stroke. A growing tumor mass might compress nearby blood vessels, restricting blood flow and increasing the risk of clot formation or vessel damage. Tumor cells can also directly invade arterial or venous sinuses, disrupting normal vascular function.
Fragments of the tumor, known as tumor emboli, can break off and travel through the bloodstream. If these emboli reach the brain, they can block a blood vessel, causing a stroke. Intratumoral hemorrhage, or bleeding within the tumor, can also occur, particularly in certain aggressive tumor types like gliomas or metastatic brain tumors. This bleeding can directly damage brain tissue or increase pressure within the skull, leading to stroke-like symptoms.
Cancer Treatment Side Effects
Various cancer treatments can also contribute to an increased risk of stroke. Chemotherapy agents, particularly platinum compounds like cisplatin, have been linked to cerebrovascular events. Some chemotherapies may damage the endothelial cells lining blood vessels, promoting clot formation.
Radiation therapy, especially when directed to the head, neck, or chest, can induce changes in blood vessels over time. This can lead to vasculopathy, characterized by thickening of vessel walls and the formation of atherosclerotic plaques, which narrow the arteries and increase stroke risk. These effects can manifest years after treatment. Surgical interventions for cancer can also elevate the risk of thromboembolic events by promoting a procoagulant state or causing temporary blood stasis.
Paraneoplastic Syndromes
Paraneoplastic syndromes are rare disorders that occur when the immune system’s response to cancer inadvertently affects healthy tissues, including blood vessels and clotting mechanisms. These syndromes are not caused by the tumor’s direct presence or metastasis, but result from substances produced by tumor cells or the body’s immune reaction to the tumor.
In the context of stroke, paraneoplastic syndromes can induce a hypercoagulable state by causing the tumor to release procoagulant substances. This can lead to abnormal blood clotting, resulting in cerebral infarction. While less common, paraneoplastic vasculitis, an inflammation of blood vessels, can also contribute to stroke by damaging vessel walls.
Types of Strokes Associated with Cancer
Stroke in cancer patients can manifest as either ischemic or hemorrhagic. The most common type observed in individuals with cancer is ischemic stroke, accounting for a majority of cases. This type occurs when a blood clot blocks an artery supplying blood to the brain, often stemming from the hypercoagulable state induced by cancer or its treatments. Elevated levels of D-dimer, a marker of clot degradation, are frequently observed in cancer-associated ischemic strokes.
Hemorrhagic stroke, which involves bleeding into the brain, is less common in cancer patients but can still occur. This type of stroke may result from specific tumor types, such as brain tumors or metastases that are prone to bleeding, or from certain cancer treatments that affect clotting. Leukemias, particularly acute forms, are more commonly associated with brain hemorrhages than solid tumors. Disseminated intravascular coagulation (DIC), a severe clotting disorder that can lead to both excessive clotting and bleeding, can also result in hemorrhagic stroke in cancer patients.
Recognizing Stroke Symptoms
Recognizing stroke symptoms promptly is important, especially for individuals with a cancer diagnosis. Immediate medical attention can improve outcomes. Stroke symptoms often appear suddenly.
A simple way to remember common indicators of stroke is the FAST acronym:
- F: Face drooping – one side of the face sags or feels numb, and their smile appears uneven.
- A: Arm weakness – one arm is weak or numb, or they cannot raise both arms equally.
- S: Speech difficulty – slurred speech, trouble understanding, or difficulty repeating simple phrases.
- T: Time to call emergency services immediately if any of these signs are present.
Other symptoms can include sudden numbness or weakness on one side of the body, sudden blurred or lost vision, sudden severe headache, or sudden dizziness and loss of balance. Even if symptoms are temporary, prompt medical evaluation is necessary.