The first 3 months after cancer diagnosis is a critical period for stroke risk, and patients with lung or pancreatic cancers are most vulnerable, a nationwide study from Israel finds.

Among over 180,000 patients with a first cancer diagnosis, the risk of ischemic stroke peaked during the first 3 months post-diagnosis, at an incidence rate 2.5 times that of the general population. Patients with lung or pancreatic cancer faced the highest risks during that early period and for the first year after diagnosis.

At 1 year, stroke incidence was six times higher among patients with pancreatic cancer vs the general population and four times higher for those with lung cancer, according to findings published on September 8 in Cancer.

“Our findings suggest that attention to vascular risk may be particularly important soon after cancer diagnosis, especially in patients with higher-risk cancer types,” said lead researcher Carmit Libruder, MSc, of the University of Haifa and the Israel Center for Disease Control in Ramat Gan, Israel.

She stressed, however, that the absolute risks were moderate, ranging from about three strokes per year for every 1000 patients with breast cancer to about 16 per 1000 patients with pancreatic cancer.

It’s known that people with cancer generally have elevated risks of both hemorrhagic and ischemic stroke. But the magnitude of the risk according to cancer type, and the time periods of greatest risk, are not fully understood.

To investigate, Libruder and her colleagues conducted a retrospective cohort study linking the Israel National Cancer Registry and the Israel National Stroke Registry. They identified 182,221 residents aged 40 years or older diagnosed with a first-time invasive cancer between 2014 and 2021, then looked at their incidence of a first-ever ischemic stroke within one year.

Overall, the cumulative incidence of stroke was 0.62%, corresponding to a standardized incidence ratio (SIR) of 1.8 (95% CI, 1.7-1.9). The excess risk peaked during the first 3 months after diagnosis, at an SIR of 2.5 (95% CI, 2.2-2.7), before dropping to 1.5 at 6-12 months (95% CI, 1.3-1.6).

Stroke risks were significantly increased for patients with all malignancies other than breast and prostate cancers. The risk was highest in patients with lung or pancreatic cancers, who had cumulative 1-year incidences of about 1.3% and 1.6%, respectively.

“This supports a more targeted approach to cerebrovascular risk assessment, rather than treating all patients with cancer as having the same level of risk,” Libruder said.

People with lung or pancreatic cancer may be at particular risk for stroke, in part, due to modifiable risk factors such as smoking, the researchers noted. But the magnitude of the risk, and the early timing, probably also reflect prothrombotic and inflammatory features of the two cancers.

The study lacked information on patients’ comorbidities, cancer treatments, and antithrombotic medications, Libruder told Medscape Medical News. “So we could not separate the contribution of the cancer itself from that of cancer treatments or underlying vascular risk,” she said.

Stroke risks were also notably elevated among patients with esophageal or gallbladder cancers, who had SIRs similar to those of patients with lung cancer. But those estimates were based on small case numbers.

In general, SIRs declined with age, from 3.6 in adults aged 40-54 years to 1.4 among individuals 75 years or older, probably due to the low baseline incidence of stroke at younger ages, the researchers noted. In contrast, SIRs increased with cancer stage, from 1.2 in localized disease to 2.8 in metastatic disease.

Libruder said that while the findings support routinely assessing patients’ modifiable vascular risk factors during cancer care, they can’t identify an optimal strategy for doing so.

“[This] study did not evaluate specific screening or preventive strategies and, therefore, cannot determine how vascular risk assessment should be implemented or which specialty should take primary responsibility,” she said.

The authors reported receiving no funding for the study. Libruder reported having no conflicts of interest.