Certain Cancers Increase Stroke Risk, New Analysis Confirms

Donavyn Coffey

November 22, 2021

A new systematic review revealed that people living with certain cancers as well as those in remission face a significantly higher risk for stroke than people with no history of cancer.

Previous research has suggested such a link exists, but until now, the evidence has not been robust enough to elicit guidelines on stroke risk and prevention in cancer patients.

Given that historically, "cancer prognosis has been very bad, [a potential cancer-stroke link] frankly didn't matter," said Eric Yang, MD, a cardiologist and director of the Cardio-Oncology Program at the University of California, Los Angeles. He was not involved in the current study.

However, now that cancer patients are living longer, it has become critical to better understand the downstream effects of the disease and treatment and to guide clinicians on patient follow-up, according to Melanie Turner, PhD, lead author on the meta-analysis and research fellow at the University of Aberdeen, in Scotland, United Kingdom.

To quantify stroke risk in patients with a history of cancer, Turner and her colleagues reviewed 36 studies, 25 of which calculated hazard ratios (HRs) for the incidence of stroke. The authors found that the majority of these studies reported a significantly increased incidence of stroke for patients with a range of cancers — including pancreatic, lung, colorectal, breast, and ovarian cancer, as well as leukemia — though the level of risk varied across cancer types, and a handful of studies showed a lower risk or no risk for stroke in patients with cancer.

According to the review, pancreatic cancer was associated with the highest risk for ischemic and hemorrhagic stroke (HR, 2.85 and 2.28, respectively). Lung cancer was not far behind, with HRs of 2.33 for ischemic and 2.14 for hemorrhagic stroke. In addition, head and neck cancer was associated an HR of 1.54 for hemorrhagic stroke.

Other studies showed a significantly increased incidence of stroke in patients with colorectal, breast, ovarian, and nasopharyngeal cancers as well as leukemia and myeloma. Stroke risk was greatest within the first 6 months of a cancer diagnosis. Some treatments increased stroke risk, including platinum-based chemotherapy and radiotherapy in patients with head and neck cancer.

Overall, "the review found strong evidence that patients with some types of cancer have higher risk of stroke," Turner told Medscape Medical News. However, a few studies found a lower risk or no risk of stroke — specifically for cervical, prostate, gastric, and testicular cancers.

The meta-analysis was challenging to conduct, according to Turner, largely because of the heterogeneity of the studies and the fact that the relationship between stroke incidence and cancer "is not a simple one."

"Cancer type, time since diagnosis of cancer, the types of anticancer treatments received, and shared risk factors such as smoking can all influence the risk of stroke after cancer," Turner and colleagues write.

More research is needed to understand how the two are connected. "We still don't know the true cause — it's more of an association — and may be more of a combination of many things," Yang said.

Although no guidelines exist for stroke prevention or risk management for cancer patients, clinicians should be mindful that cancer can increase stroke risk. "When they're seeing patients, [clinicians should] see that as an opportunity to look for risk factors of stroke and cardiovascular diseases," Turner said.

Yang suggested that the use of statins and other cardiovascular risk mitigators for cancer patients with a high risk for stroke warrants more investigation, and for especially high-risk patients — those with lung or pancreatic cancer — oncologists should be mindful of neurologic symptoms or blood clots.

Yang and Turner noted that, given the association between stroke and some cancers, helping patients with cancer control stroke risk factors — such as obesity, diabetes, and hypertension — may be critical to prevention efforts.

"Keeping patients' stroke risk factors at bay might increase the chance they can continue their cancer treatment and improve their quality of life," Yang said.

J Cancer Surviv. Published online November 5, 2021. Full text

The authors have disclosed no relevant financial relationships.

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