What is a brain tumour?
A brain tumour is a mass of abnormal cells growing in the brain. A tumour that starts in the brain is a primary brain tumour – these rarely metastasize, or spread, outside the brain and spinal cord.
Benign tumours consist of very slow growing cells, usually have distinct borders and rarely integrate into the surrounding healthy brain. Treatment and/or surgery are often effective, however a benign tumour located in a vital area of the brain, such as the central nervous system, is life-threatening.
Malignant brain tumours are the most common cancer of the central nervous system that arise without any previous history of low-grade disease and, in the majority of patients, there is no known familial genetic abnormality. Despite treatment that combines surgery, radiotherapy and chemotherapy, malignant brain tumours remain incurable. Three biological features account for the dismal prognosis associated with these tumours: cells from the main tumour mass invade the surrounding normal brain making complete surgical removal impossible; the presence of therapy-resistant tumour cells allows the initiation of tumour re-growth after therapy; and malignant tumour cells multiply rapidly.
Despite more than half a century of research into brain tumours, they remain a leading cause of death in the western world. To date, little progress has been made in understanding how tumours form, survive and grow.
In 2008 the Queensland Brain Institute, with the support of the Australian Cancer Research Foundation, opened a tumour-cell testing facility. The $1.14m centre has enabled researchers to isolate, enumerate and purify tumour stem cells more easily.
“Until now, one of the prime difficulties in studying these stem cells was that scientists lacked the tools to identify and collect them. This technology has changed that,” QBI Director Professor Perry Bartlett said.
Individual cells within a tumour vary in size, morphology, expression and membrane composition, as well as displaying diverse functional behaviours in terms of proliferation rate, cell-to-cell interactions, metastatic potential and sensitivity to therapy. This variation is commonly referred to as ‘tumour heterogeneity’.
QBI researchers believe these variants are the key reasons tumours survive and continue growing after clinical intervention. If this hypothesis is correct, it raises significant challenges for neuroscientists attempting to develop treatments.
Tumour researchers say the current therapy of radiation plus the medicine known as TMZ (the oral treatment temozolomide) is increasing patient survival time but the problem is that it creates more mutations and the patient still dies as a result of their tumour. Recurrent tumours are much more aggressive, no longer respond to therapy and cause more long-term brain problems.
Armed with this knowledge the neuroscientists can now develop other treatments and tailor existing therapies so they are tumour-specific.