Around 85% of strokes are ischemic strokes. They are frequently caused by the blocking of arteries connected to the brain.
In addition, stroke survivors who develop cancer are three-times more likely to die in comparison with survivors who do not develop cancer, according to research presented at the American Stroke Association's International Stroke Conference this year.
Previous research has connected cancer with an increased risk of stroke. Cancer can cause hypercoagulation (excessive blood clotting), and this can be an important stroke risk factor in patients with this disease.
In particular, ischemic strokes - the most common form of stroke - occur when arteries connecting to the brain become blocked or narrowed. Blockages are often caused by blood clots, and so excessive blood clotting increases the risk of arteries becoming obstructed.
"We already knew that cancer patients are at increased risk of stroke," says lead author Dr. Malik Adil. "But what happens when you turn it around and look at cancer risks for ischemic stroke survivors? That was our question."
For the study, a research team at the Zeenat Qureshi Stroke Institute in St. Cloud, MN, analyzed data taken from the Vitamin Intervention for Stroke Prevention (VISP) trial. The VISP was a multicenter trial running from 1997 to 2001.
The researchers examined data for 3,247 cancer-free participants aged over 35 who had each suffered a mild ischemic stroke. These were compared with data from the National Cancer Institute demonstrating cancer rates and the risk of death and other cardiovascular events for the general population.
Stroke survivors had a higher likelihood of developing cancer and death
Differences in cancer rates between the participants who had ischemic strokes and the general population were calculated for 1 month, 6 months, 1 year and 2 years after stroke.
After adjusting for age, the researchers found that the annual rate of cancer incidence was higher among the stroke patients in comparison with the rates for the general population.
The rate of cancer occurrence among stroke survivors also increased over time. At one year after stroke, the rate of cancer was 1.2 times higher than the general population, and this increased to 1.4 times higher a year later.
Developing cancer also meant stroke survivors were far more likely to die. The authors observed that those that got cancer were up to three times more likely to die when compared with those that did not develop the disease.
Dr. Adil suggests that "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."
In addition to ischemic stroke, age was identified as a risk factor for developing cancer. Stroke survivors aged over 50 were 1.4 times more likely to develop the disease than participants aged 50 and below.
In the study, a wide range of cancers was reported. Bladder, breast, lung, prostate and skin cancer were all identified among the participants. Dr. Adil believes that increased cancer incidence is an important matter to be discussed by stroke survivors with their health care providers.
"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," he says. "Factors that may put a person at higher risk for developing cancer include: cigarette smoking, alcohol consumption and a family history of cancer."
Recently, Medical News Today reported on a study showing that paramedics could feasibly administer life-saving drugs to stroke patients before they arrive at hospital, greatly improving their chances of returning to a normal life afterwards.