Cancer patients having a stroke are one-third less likely than stroke patients without cancer to get a gold-standard drug to help dissolve the clot, researchers reported Friday.

Strokes in cancer patients can be caused by traditional risk factors such as high blood pressure. But cancer, which can cause blood to clot more easily, and its treatments, are also associated with an increased stroke risk.

The study, led by Dr. Babak Navi, a neurologist at Weill Cornell Medicine in New York City, used data collected through the National Inpatient Sample from 1998 to 2013 on patients hospitalized for an acute ischemic stroke. These strokes are caused by a blood clot that blocks a vessel in the brain.

The use of both the clot-dissolving drug called alteplase and medical procedures to remove clots in stroke patients has increased since 1998. The study found that in cancer patients who had a stroke, the use of clot-busting medication rose from 0.01 percent in 1998 to 4.23 percent in 2013. But in patients who did not have cancer, medication use increased from 0.02 percent to 6.38 percent during the same time period.

The use of newer procedures to mechanically remove clots rose from 0.05 percent in 2006 to 1.07 percent in 2013. The increased use was seen in both patients with and without cancer.

Navi presented the findings at the American Stroke Association’s International Stroke Conference in Los Angeles.

An August 2017 study by Navi and his colleagues published in the Journal of the American College of Cardiology found an increased risk for a stroke or heart attack among patients newly diagnosed with cancer. That study found that 4.7 percent of Medicare cancer patients had a heart attack or stroke within six months of their diagnosis compared to 2.2 percent of Medicare patients who did not have cancer.

Although the study can’t explain why cancer patients are less likely to get clot-busting medication, Navi said he suspects that cancer patients may get them less often because they have been on blood thinners or have a low blood platelet count. In addition, he said, some cancer patients may not get these drugs because they aren’t expected to do well “which causes a self-fulfilling prophecy.”

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