Gord Downie’s incurable cancer: 5 things about glioblastoma

Daily Brew

The Tragically Hip, announced Tuesday morning that lead singer Gord Downie has terminal brain cancer. But “brain cancer” is a term that encompasses a variety of different diagnoses, with a range of prognosis from very promising to terminal. 

Downie, 52, had a seizure in his hometown of Kingston, Ont.,  and as a result he was diagnosed in December with a deadly form of brain cancer. He has since had surgery that removed a large portion of the cancer, along with six weeks of treatment with radiation and chemotherapy, and is currently doing well, neuro-oncologist Dr. James Perry of Sunnybrook hospital said at a news conference in Toronto on Tuesday morning.

There are more than 120 types of brain and central nervous system tumours, according to the National Brain Tumour Society. Here are five things to know about brain cancer, and Downie’s specific diagnosis.

What is brain cancer?

A brain tumour, most simply, is a mass of abnormal cells growing in the brain. These masses can be benign (non-cancerous) or malignant (cancerous). The type of malignant brain tumour Downie was diagnosed with is called glioblastoma or GBM, which makes up the 12 to 15 per cent of all types of brain tumours, according to the Canadian Cancer Society

Glioblastoma is a type of cancer that originates in the brain and is called a glioma, which refers to a cancer formed in the glial (supportive) brain cells as opposed to the neurons. This type of tumour generally develops in the cerebral hemispheres of the brain, and Downie’s in particular is in the left temporal lobe.

U.S. Senator Ted Kennedy and Beau Biden, the son of Vice-President Joe Biden, also had gliomas, and in both their cases the cancer was fatal.

What causes glioblastomas?

The cause of 99 per cent of these glioblastomas is unknown, Dr. Perry said at the news conference. There are a few occupational risks — for example, among firefighters working in hazardous materials units — but even that increased risk is limited, Dr. Perry said. However, some research has indicated that the cancer is related to an as-yet-unknown genetic mutation. And it is known that glioblastomas are more common in men, adults aged 50 or older, and people of Caucasian or Asian ancestry, according to the MD Anderson Cancer Center at the University of Texas.

Is glioblastoma responsive to treatment?

Because it’s such a deadly type of cancer, glioblastomas were the first type of brain tumour sequenced as part of the Cancer Genome Atlas. That work revealed that there are four distinct genetic subtypes of the cancer, and those types all respond differently to treatment.

During the news conference, Dr. Perry remarked that the biomarkers on the singer’s tumour indicated it’s of a type that is generally more responsive to treatment and comes with a better chance of longer-term survival. Downie has received both radiation and chemotherapy as treatment and while his type of cancer is aggressive, it has responded well.

What are the symptoms of this kind of brain cancer? 

For Downie, the sign of trouble came in the form of a seizure and it’s one symptom of glioblastomas (and other types of brain tumour). Other symptoms include motor weakness, headaches, cognitive impairment, nausea and vomiting. Other symptoms can depend on where the tumour is located — for example, a patient could have sensory symptoms like blurred vision or speech difficulties.

What is the prognosis?

Though the Tragically Hip musician has responded well to surgery and treatment thus far, Downie’s cancer is incurable. His tumour is currently quite small thanks to surgery and treatment, Dr. Perry said at the news conference, and it’s difficult to say anything at this point about survival times, though Downie has been cleared to tour. But the cancer will eventually come back, Dr. Perry said.

Glioblastomas are the deadliest of the malignant primary brain tumours seen in adults, according to the National Brain Tumour Society, with a median survival rate of 15 months and a five-year survival rate of about four per cent.