The prognosis for patients with gliomas varies, depending on what type of cells are affected, how far the tumour has developed, where it is, and how well it responds to treatment. Cure is very unlikely. According to the US Society for Neuroscience, glioma is diagnosed in about 20,000 Americans every year and more than half die within 18 months.

In the best situation, patients may survive for five years; in the worst, for less than a year. Without more detail it is impossible to know to which category Mr Kennedy belongs.

Gliomas are tumours of the glial cells, the supporting cells of the brain. The symptoms vary, depending upon which part of the brain is affected. They can cause seizures of the type Mr Kennedy suffered, or more modest symptoms such as headaches, nausea, and vomiting. A glioma of the optic nerve can cause visual loss. Treatment is usually by a combination of surgery, drugs, and radiation. Some new therapies have been tried, including gene therapy, but results have not been overwelmingly impressive.

The hospital statement says that Mr Kennedy’s glioma is in the left parietal lobe of the brain. Tumours in this region often cause seizures, and may also cause speech disturbances and the loss of ability to write. Spatial disorders, such as difficulty with body orientation in space or recognition of body parts, may also occur.

Some doctors have claimed greater success for treatments based on intensive use of drugs such as methotrexate. But gliomas vary so greatly that generalising about treatment success without the details is meaningless.

It is safe to assume that Mr Kennedy will get the best treatment US medicine can provide, and that is very good. But a diagnosis of a malignant glioma is very bad news indeed.

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