People who had a stroke may develop cancer at a higher rate than those who do not have a stroke, according to research presented at the American Stroke Association's International Stroke Conference 2015.
"We already knew that cancer patients are at increased risk of stroke. But what happens when you turn it around and look at cancer risks for ischemic stroke survivors? That was our question," said Malik Adil, M.D., lead author from the research team at the Zeenat Qureshi Stroke Institute in St Cloud, Minnesota.
The team analyzed data from theVitamin Intervention for Stroke Prevention (VISP) multicenter trial from 1997 to 2001. The analysis consisted of 3,247 cancer-free participants over the age of 35 who had a mild ischemic (clot-caused) stroke.
The annual rate of age-adjusted cancer incidence was higher among ischemic stroke patients compared with the general population.
The rate of cancer occurring among stroke survivors was 1.2 times higher at one year, and 1.4 times higher at two years.
Stroke survivors who developed cancer had up to three-times higher chance of dying compared to those who didn't get cancer.
Having cancer is linked to higher ischemic stroke risks mainly because cancer patients' blood tends to clot more often, Adil said. "In addition, when tissues get less oxygen due to blocked blood vessels, it destroys tissue cells and sets off a series of events to alter the normal physiology and may lead to cancer."
Another risk factor for developing cancer was age. The study showed stroke survivors over age 50 were 1.4 times more likely to develop cancer within two years than their counterparts who were age 50 and under.
The researchers used National Cancer Institute data for the general population's cancer rates. Then they calculated cancer rate differences between the stroke and non-stroke groups at one month, six months, one year and two years.
They also calculated the risk of death and other cardiovascular events, and compared those findings between stroke survivors who did and didn't develop cancer.
Participants developed a wide range of cancers, including skin, prostate, breast, lung and bladder cancer.
"If you've had a stroke before, especially with another high-risk factor, it's important that you talk to your doctor and discuss earlier cancer screening," said Adil. "Factors that may put a person at higher risk for developing cancer include: cigarette smoking, alcohol consumption and a family history of cancer.
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