Exploring the Link Between Stroke and Cancer

The link between cancer and stroke has been of interest to researchers for some time, but evidence on the topic has been limited. A new study, presented at the European Society for Medical Oncology (ESMO) 2017 Congress in Madrid, sheds some more light on this connection.

Researchers at the Hospital de La Princesa in Madrid, Spain studied the records of 914 people who came to the hospital’s emergency room (ER) with ischemic strokes, meaning that blood clots restricted blood flow to parts of the brain. Of these, 381 patients met the inclusion criteria for the study. The researchers followed these patients for a year and a half after their ER visits to see whether they developed cancer.

The percentage of stroke patients who were diagnosed with cancer within 18 months of having a stroke was 7.6 percent — almost double the rate in the general population, which is 4.5 percent. The average time from patients’ stroke onset to cancer diagnosis was six months.

Most frequently, the cancers diagnosed were of the colon, lung or prostate, and were more likely to be found in patients who were over 76 years old, had a previous cancer diagnosis, had high levels of fibrinogen (which helps the formation of blood clots) and/or low levels of hemoglobin, which carries oxygen through the blood.

Which Came First, Stroke or Cancer?

Though cancer was diagnosed after patients in the study experienced strokes, researchers hypothesize that for many, cancer had been present beforehand. By the time cancers were diagnosed in these patients, almost two-thirds (62 percent) had metastatic or locally advanced disease.

“When cancer was diagnosed, it was usually at an advanced stage,” said the study’s lead author Jacobo Rogado, M.D., medical oncology fellow, Hospital de La Princesa. “This indicates that the cancer was already present when the stroke occurred but there were no symptoms.”

He raised the possibility that because cancer is a “hypercoagulable state,” in which tumor cells activate the blood coagulation system, it would make sense for a stroke to be a related consequence.

“It may be that the prothrombotic [clotting] effect of cancer contributed to the strokes,” he suggested.

Though the results of the study are intriguing, further studies are needed before a firm association can be established between stroke and cancer. However, these results were compelling enough that Rogado recommends that in the future, stroke survivors should be monitored for the development of cancer during the first 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 specified.