Cancer after cerebral venous sinus thrombosis? Not screening, but extra alert

Cancer is a risk factor for thrombosis, including thrombosis in the brain. But is thrombosis in the brain also a signal for a higher chance of a cancer diagnosis in the following years? In a publication in JAMA Network, researchers from Amsterdam UMC and Radboudumc show that the risk is indeed higher, especially for men over 50. Based on this study, screening is not (yet) necessary, but extra alertness is.

Cancer is a known risk factor for the development of thrombosis, of occlusions in the blood vessels. So is the development of cerebral venous thrombosis (CVT), a stroke caused by a blocked vein in the brain. This is a different type of stroke than cerebral infarction, where the blockage is in the artery.

People with cancer are five times more likely to have a CVT than people without cancer. This risk is highest in the first year after cancer diagnosis. About five to 10 percent of patients with CVT have a history of cancer when they have a CVT.

Few data

“We would like to know whether CVT can also be a manifestation of a cancer that is already present at the time but not yet diagnosed, or whether cancer will develop after such a CVT,” says Jamie Verhoeven of the Radboudumc. “Unfortunately, little is known about that yet. Recently, though, two small studies have been done on it. A Finnish study found that over two percent of CVT patients were diagnosed with cancer in the first two years after diagnosis, especially in patients over 50. In a Danish study, more than five percent were diagnosed with cancer after more than six years, but that percentage was little different from the general population. Both studies examined only a small group of patients, making the results somewhat less robust and reliable.”

Digging into the database

Why are these data important? Because CVT might alert both doctors and patients to an increased risk of cancer. At least if the data show that, because according to current guidelines, screening for cancer is not necessary. To get more data, a group of researchers from Amsterdam and Nijmegen have now conducted a larger study in the Netherlands. Anita van de Munckhof of the Amsterdam UMC: “With these figures, we can better estimate how often CVT patients are diagnosed with cancer in subsequent years. Furthermore, we wanted to determine which groups of patients have the highest risk. To do this, we started digging into the data of the National Basic Hospital Care Registry combined with the population register of the Central Bureau of Statistics. Over a period of more than 20 years (1997-2020), we found more than 2,600 patients with CVT with an average age of just over 44 years.”

Extra alert

“We analyzed the number of newly diagnosed cancers in the ten years after a first CVT diagnosis,” says Verhoeven, ”and compared this number with the numbers in the average population using IKNL's National Cancer Registry. This shows that in both men and women with CVT, the risk of cancer is indeed somewhat higher than in the average population.” Van de Munckhof adds: “Within that, we see that men over 50 are at greatest risk. Our advice based on this study is that doctors should pay close attention to possible symptoms of cancer in these patients. Screening is not yet warranted, but that could change in the future based on more research in this patient group.”

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Publication in JAMA Network Open / Neurology: Incidence of Newly Diagnosed Cancer After Cerebral Venous Thrombosis - Anita van de Munckhof, MD; Jamie I. Verhoeven, MD; Ilonca C. H. Vaartjes, PhD; Nick van Es, MD, PhD; Frank-Erik de Leeuw, MD, PhD; Jonathan M. Coutinho, MD, PhD

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