What is glioblastoma and why is it so hard to treat?

The death of former Australian of the Year Richard Scolyer overnight came after a multi-year fight with one of the most difficult to treat cancers.

Glioblastoma is known as the most aggressive form of brain cancer.

And while there have been vast improvements in our ability to treat other cancers, such as melanoma, survival rates for this fast-growing brain cancer remain stubbornly low despite years of research and funding.

So what is it about glioblastoma that makes it so hard to treat?

What is glioblastoma?

Glioblastoma is part of the glioma family of tumours, and is a serious and aggressive stage 4 brain cancer.

Professor Lenka Munoz, a professor of molecular cancer pharmacology, says these tumours develop from glial cells, which support neurons in the brain.

"It accumulates several mutations, then becomes malignant and starts proliferating without control.

"These cells keep on dividing, and eventually form a small tumour," she says.

The tumours are difficult to treat and largely resistant to chemotherapy.

Average survival rates are between 12–18 months, with just five per cent of patients surviving longer than five years.

How many people are affected by glioblastoma?

Nearly half of all primary malignant brain tumours are glioblastoma.

It's estimated that roughly 200,000 people die per year worldwide, including 1,000 Australians.

Professor Scolyer was diagnosed in June, 2023, after suffering a seizure while in Europe.

He acted as "patient zero" for a world-first immunotherapy treatment prior to surgery, which temporarily removed the tumours.

US politician John McCane died from glioblastoma in 2018.

Other notable deaths from glioblastoma include fashion designer Yves Saint Laurent, Ted Kennedy, Joe Biden's son Beau, and author Sophie Kinsella who died in 2025.

Glioblastoma affects more males than females, and the median age of patients is 64.

What causes it?

It's currently unclear whether lifestyle factors or genetics play a part in risk factors.

There is no known cause of glioblastoma, Professor Munoz says.

"There is not one clear mutation that we could use as a diagnosis — we don't know why patients develop glioblastoma," she says.

Is there treatment?

Early detection can improve outcomes however glioblastoma remains one of the most difficult cancers to treat.

Current medical interventions include surgery to remove tumours followed by chemotherapy and radiation.

Unfortunately, glioblastoma commonly returns soon after treatment.

Why is it so difficult to treat?

Glioblastomas are difficult to treat for a number of reasons.

John Simes, a medical oncologist on the board of Brain Cancer Australia says glioblastoma tumours are diffusive (not contained) and often have roots in different parts of the brain.

This means it's no possible to remove all the tumour.

"The reason the surgery is done is to debulk the tumour. Then radiotherapy is given."

Gliobastoma tumours are also often in difficult-to-reach areas, which makes operating dangerous.

"There are organs where surgeons can remove large parts of an organ and the patient can still live, whereas this is not possible in the brain," Professor Munoz says.

There are also challenges in getting medication into the brain, which makes treating any tumour not removed by surgery difficult.

"It's very difficult to get drugs into the brain because the brain is protected by the blood-brain barrier," Professor Munoz says.

"The barrier is there to protect us from viruses, microorganisms, and bad substances."

Chemotherapy can kill some of the different types of cells, but there will typically remain a small sub-population of drug tolerant "persistor" cells.

Professor Munoz says these cells will remain in the brain, dormant, and not visible on scans. They typically lead to a recurrence of the tumour.

"They sit there for weeks, months and then, eventually they start growing again," she says.

What are the symptoms?

Symptoms of glioblastoma can be gradual and undetectable at first.

"If you've got a very small tumour in the brain, then usually you won't be aware that it's there," Professor Simes says.

"By the time it starts to show symptoms, it's usually going to be a larger size, maybe a few centimetres or longer."

Headaches, confusion, memory loss, motor weakness, and seizures are common.

"And so often you might pick this up when it's causing problems of brain swelling, which would be from a large tumour," Professor Simes says.

"So if you're getting headaches or nausea and vomiting, that would be from a large tumour with delayed symptoms."

Personality changes, difficulties concentrating and speech struggles are among some other symptoms experienced by patients.

Future hopes for glioblastoma treatment

There have been several progressions in treatment, however no definitive solution has yet been found.

Professor Scolyer opted for an immunotherapy treatment prior to surgical intervention in a world-first.

He delayed removing the brain tumour to undergo immunotherapy and receive a vaccine personalised to his tumour markers.

Professor Scolyer managed to keep the cancer at bay for nearly two years, but in March 2025, announced the tumours had returned.

Other research, led by Professor Munoz published late last year in the journal Nature Communications, has found that some groups of cells within a glioblastoma are resistant to chemotherapy due to a fertility gene — they would lie dormant after treatment before regenerating the tumour.

"What we found is that they use this fertility gene to reprogram their metabolism, and constantly produce new cholesterol, which is crucial for cells to survive," Professor Munoz says.

Professor Simes says while both areas of research "have the potential to be promising", it is still early days.

"There's been a number of things in the past which have been promising which, once they've been finally put to the test turned out to be disappointing."

But Professor Munoz believes a combination of therapies will ultimately, and hopefully, be the answer.

"For cancer as aggressive as glioblastoma, I think there's a consensus in the field that it will be not only chemo or immunotherapy — it will be a combination."

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