MADRID, Spain — Some stroke patients may have undiagnosed cancer that is contributing to their risk for cerebrovascular events by inducing a state of hypercoagulability, the results of a Spanish observational study suggest.
The incidence of cancer among stroke survivors was almost twice the rate that would be expected in the general population and was associated with increased serum fibrinogen levels.
"When cancer was diagnosed, it was usually at an advanced stage, and the diagnosis was made within 6 months after a stroke," lead researcher, Jacobo Rogado, MD, medical oncology fellow, Hospital de La Princesa, Madrid, Spain, said in a statement.
"This indicates that the cancer was already present when the stroke occurred but there were no symptoms," he added.
"Stroke survivors should be followed clinically for the development of cancer in the 18 months after the diagnosis of stroke. This applies particularly to older patients who had cancer previously, or who have high fibrinogen or low levels of hemoglobin," he said.
The study will be presented here at the European Society for Medical Oncology (ESMO) 2017 Congress on September 10.
Commenting for ESMO, Fausto Roila, MD, director of medical oncology, Santa Maria della Misericordia Hospital, Perugia, Italy, sounded a note of caution over interpreting the results.
While the potential association between stroke and cancer "is an interesting issue," he said, the current results are hampered by the lack of a matched control group. "A case-control study would have been more suitable," he said in a statement.
Dr Roila also pointed out that the difference in absolute numbers between incident cancer cases and that expected in the general population is only 12, "and this could be due to differences in age between the two groups."
He said, "The general population includes people of all ages, while the case population (patients with stroke) is primarily older patients. Therefore, further studies are needed before a firm association can be established between stroke and cancer."
Previous postmortem studies have suggested that cancer may be associated with stroke, potentially as a result of hypercoagulability caused by the tumor, "but the magnitude of this association has not been described," said Dr Rogado.
To investigate the association further and to identify potential predictive factors, the researchers examined the medical records of all 914 patients admitted to a single emergency department between 2012 and 2014.
The researchers excluded patients with, among others, active cancer or a cancer in the previous 5 years, transient ischemic attack, or cerebral hemorrhage. They included 381 patients with ischemic stroke and followed them up for 18 months from diagnosis, comparing demographic and clinical data between those who did and did not develop cancer.
During follow-up, 29 (7.6%) stroke patients were diagnosed with cancer, against an estimated background rate in the general population of 17 (4.5%). The most common cancer diagnoses were colon, lung, and prostate cancers, and 62% of patients had metastatic or locally advanced disease.
The mean interval between ischemic stroke onset and the diagnosis of cancer was 6 months, with 44.8% of cancers diagnosed in the first 6 months.
Multivariate analysis revealed that independent predictors of cancer diagnosis following ischemic stroke were age older than 76 years (P = .003), cancer diagnosis more than 5 years previously (P = .042), fibrinogen levels greater than 450 mg/dL (P = .019), and hemoglobin levels less than 13 g/dL (P = .004).
There was no association between cancer diagnosis after stroke and other thromboembolic risk factors, nor with the cause and clinical presentation of the stroke, the team notes.
Dr Rogado said, "It has been suggested that cancer is a hypercoagulable state in which tumor cells activate the coagulation system."
"This could explain our observation of higher fibrinogen in those who were diagnosed with cancer. It may be that the prothrombotic effect of cancer contributed to the strokes."
The authors have disclosed no relevant financial relationships.
European Society for Medical Oncology (ESMO) 2017 Congress. To be presented September 10, 2017. Abstract 1412P_PR.
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