Cancer Can Affect Blood Clotting, Which May Explain Higher Stroke Risk
Although the study was not designed to determine which mechanisms were responsible for the increased risk, Dr. Libruder speculates that cancer-related effects on blood clotting and inflammation may play a greater role during this early period.
Adults diagnosed with pancreatic cancer experienced the highest stroke rates (5.9 times that of the general population), followed by lung cancer patients (3.9 times the rate of the general population). “These cancers are more likely to cause a condition called hypercoagulability, where the blood is ‘stickier’ and more likely to form blood clots, which in turn can cause stroke,” says Maarten Lansberg, MD, PhD, a professor of neurology and co-director of Stanford’s Stroke Recovery Program in Palo Alto, California, who wasn’t involved in the new study.
Other types of cancer that showed excess risk were gallbladder and esophageal, but these estimates were based on a limited number of events, according to the authors.
The analysis also revealed significant stroke risk elevations for adults diagnosed with bladder, stomach, and liver cancers, as well as myeloid leukemia and malignant brain and nervous system tumors.
“I think the main point is that the increase in stroke risk varied across cancer types,” says Libruder. “Larger studies will be needed to confirm some of these associations.”
Cancer Diagnosed at Earlier Stages Posed Lower Stroke Risk
Breast and prostate cancers were not linked to a higher stroke risk. These cancers are often detected at early stages because established early-detection strategies are available, Libruder says.
“Consistent with this, metastatic disease [which has spread to other parts of the body] was less common in breast and prostate cancers in our study than in lung and pancreatic cancers, which had much higher stroke risks,” she says.
Among patients with cancer that hadn’t spread to other parts of the body, stroke risk was just 1.2 times the rate of the general population. But among adults diagnosed with metastatic cancer, the risk was 2.8 times that of the general population. When cancer is more advanced, Dr. Lansberg says, there are more tumor cells excreting proteins that cause risky blood clots.
Stroke Awareness Is Critical for Cancer Patients
Lansberg describes the study as “confirmatory,” backing up the findings of previous research with a very large database. The researchers, however, were not able to access detailed information on individual heart risk factors, cancer treatments, or medications, so they could not separate the effects of the cancer itself from those of treatment or underlying heart risks.
The study authors stress that the first few months after cancer detection are an especially critical time to be aware of stroke risk.
“The marked variation across cancer types, with particularly pronounced risk elevations in pancreatic and lung cancers, highlights the importance of identifying patients who may benefit from closer cerebrovascular risk assessment,” says Libruder.
- Balance: sudden loss of balance or coordination
- Eyes: sudden changes in vision or blurred sight
- Face drooping: one side of the face droops or feels numb
- Arm weakness: one arm is weak or numb, and may drift downward
- Speech difficulty: slurred speech or trouble understanding speech
- Time to call 911: Call emergency services immediately if you see any of these signs. Prompt treatment after a stroke can help minimize damage and improve survival.
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