What are the chances of chemotherapy causing a stroke?

A fellow caregiver asked...

What are the chances of chemotherapy causing a stoke? We are concerned about an 81 year old male with multiple health problems. Will the chances of chemotherapy causing a stroke be higher due to his age and previous health issues?

Expert Answer

James Castle, M.D. is a neurologist at NorthShore University HealthSystem (affiliated with The University of Chicago) and an expert on strokes.

In my experience, chemotherapy does not typically cause ischemic (non-bleeding) strokes. In general, ischemic strokes are much more common than hemorrhagic (bleeding) strokes, and are caused by a blockage in a blood vessel that supplies the brain.

The one exception that I can think of to the above rule is the extremely rare circumstance of chemotherapy causing a clot in one of the veins (not arteries) of the brain.

For the most part, cancer is associated with ischemic stroke because of one of two reasons. First, the presence of the cancer can cause the blood to become prone to clotting. This is why cancer patients not infrequently need to be on strong blood thinners. Second, if there is radiation to one of the arteries of the neck or head, this can rarely lead to an inflammation of the arteries many months or years later (known as radiation vasculitis).

In general, I would not let a fear of ischemic stroke stop someone from getting chemotherapy.

There is a second cause of stroke, hemorrhagic (or bleeding stroke), which can occur if the chemotherapy causes the platelet count to run too low. Some chemotherapies, but not all, can cause the body to shut down platelet production. Platelets are responsible for limiting bleeding, and if the platelet count in the blood stream is running dangerously low, a hemorrhagic stroke can sometimes occur. The best way to prevent this is to make sure that the patient's doctors are watching his blood counts closely.

Good luck!