Stroke risk was highest in the first three months after a cancer diagnosis
What happened
A large study published on 9 September 2026 has found that people are more likely to have a stroke in the months right after a cancer diagnosis than would otherwise be expected. The research appears in the journal Cancer, which is published by Wiley. It was led by Carmit Libruder at the University of Haifa, working with Israel's Ministry of Health. The team linked two national registries: the National Cancer Registry and the National Stroke Registry. That let them follow a very large group without relying on people remembering their own history. They looked at 182,221 adults aged 40 and over who were diagnosed with a first invasive cancer between 2014 and 2021. They then counted how many had an ischaemic stroke - the type caused by a blocked blood vessel in the brain - within a year. Across the whole year, there were about 80 per cent more strokes than would have been expected, at roughly 62 strokes per 10,000 people. The risk was not spread evenly through that year. In the first three months after diagnosis, the stroke rate was about two and a half times higher than expected. It also varied a great deal by cancer type. Pancreatic cancer carried the highest excess, at 5.9 times the expected rate, or about 162 strokes per 10,000 people. Lung cancer came next, at 3.9 times. For breast cancer and prostate cancer, the researchers found no excess stroke risk at all.
Why this matters
Around 400,000 people in the UK are diagnosed with cancer each year. The weeks after that diagnosis are already crowded with scans, appointments and decisions. A stroke on top of that is serious in its own right, and it can also delay or complicate cancer treatment. The value of a study like this is that it tells doctors where to look. If the extra risk were spread evenly across every cancer and every month, there would be little to act on. Because it is concentrated in specific cancers and in a specific window, it points to a group of patients who might benefit from closer attention. It matters for families too. Knowing the warning signs of stroke is useful for everyone, but it is especially useful when someone you love has just been diagnosed with pancreatic or lung cancer and you are already spending time with them. That is not a reason to be frightened. Most people with cancer will not have a stroke. It is a reason to know what to watch for.
What the evidence actually says
This was a registry study. It compared what actually happened with what would have been expected in the general population of a similar age. That design is good at spotting patterns across very large numbers. It is not designed to explain why the pattern exists. The researchers are clear that they have found an association, not a cause. They did not test any mechanism. There are several plausible explanations, and they may all play a part. Some cancers make the blood more likely to clot. Some treatments, including certain chemotherapy drugs, affect blood vessels and clotting. A tumour can press on a vessel. People newly diagnosed with cancer may also be less active, dehydrated, or having surgery, all of which raise clot risk. The variation between cancers is a real clue. Pancreatic cancer is already well known for increasing clotting risk. Breast and prostate cancers, which showed no excess here, are less associated with that effect. Two other findings are worth noting. Younger patients and those with more advanced disease showed higher risk. That is a reminder that "younger" does not mean "safe" here. One limitation to hold in mind: the data come from Israel. Cancer care, stroke care and background stroke rates differ between countries, so the exact numbers may not transfer directly to the UK. The overall direction of the finding fits with earlier research elsewhere. The corresponding author summed up the practical point: "The marked variation across cancer types... highlights the importance of identifying patients who may benefit from closer cerebrovascular risk assessment."
Practical advice
The single most useful thing anyone can take from this study is knowing how to spot a stroke. In the UK the NHS uses the word FAST: Face - has their face fallen on one side? Can they smile? Arms - can they lift both arms and keep them there? Speech - is their speech slurred or muddled? Time - if you see any of these signs, ring 999 immediately. Stroke treatment is extremely time-sensitive. Clot-busting treatment and clot removal work best within a few hours. Do not wait to see if it passes. Do not drive the person yourself unless an ambulance cannot come. If you or someone close to you has recently been diagnosed with cancer, it is reasonable to ask the oncology team whether anything in the treatment plan affects clotting risk, and whether blood-thinning medicine is being considered. Some patients are already offered it. Mention any existing risk factors at your appointments: high blood pressure, atrial fibrillation, diabetes, smoking, or a previous stroke or mini-stroke. These matter more, not less, during cancer treatment. Keep taking blood pressure and other regular medicines through cancer treatment unless your team tells you otherwise. It is common for routine medicines to slip during an intense period of appointments, and that is exactly when they are needed. If you notice sudden severe headache, sudden loss of vision, sudden confusion or sudden difficulty walking, treat it as an emergency.
What to know
A study of 182,221 people found roughly 80 per cent more ischaemic strokes than expected in the year after a first cancer diagnosis, with the rate about 2.5 times higher in the first three months. The risk was heavily concentrated: pancreatic cancer 5.9 times expected, lung cancer 3.9 times, and no excess risk at all for breast or prostate cancer. This is an association from registry data in Israel, not proof of cause, and the mechanisms were not tested. It does not mean a stroke is likely for any individual. The useful takeaway is simple. Learn FAST, act on it immediately, and raise clotting and blood pressure with your cancer team if you have not already. Sources: Medical Xpress, "Stroke risk higher in first three months after cancer diagnosis, study finds", 9 September 2026, https://medicalxpress.com/news/2026-09-higher-months-cancer-diagnosis.html ; Libruder C et al., "Cancer", Wiley, 2026, DOI 10.1002/cncr.70536, https://doi.org/10.1002/cncr.70536 ; NHS, "Stroke - symptoms", https://www.nhs.uk/conditions/stroke/symptoms/ This article is for general information and does not replace advice from a doctor, pharmacist or other qualified healthcare professional. If you think someone is having a stroke, ring 999 straight away.
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