Pretoria - Tumours in the brain and nervous system are increasing, according to the cancer registries of many Western countries.
Some specialists say the increased prevalence could be due to better diagnosis of conditions previously attributed to strokes or dementia.
Others say that patients with cancer in other parts of the body are surviving longer due to better treatment, and that cancer cells are spreading to the brain or nervous system.
No one is saying there is an epidemic, and the prevalence of brain tumours in the general population is still low.
But even taking into account better diagnosis and survivability of cancer patients, the extent of the rise is worrying, even for the experts, published reports say.
The prevalence of brain tumours in South Africa is not known, because in the National Cancer Registry of 2004 (the last available), brain cancers are combined with central nervous system cancers.
At that time, it was estimated that the lifetime risk of developing a central nervous system tumour was one in 849 for men, and one in 1 611 for women.
However, according to oncologist Andre Dreyer of the GVI Oncology group, “95 percent of nervous system tumours are in the brain”.
“Brain cancers are quite common, and they affect all communities, in all age groups all over the world,” he says.
In children, he adds, although the incidence of brain tumours is low, they are the second most common cancer after leukaemia.
More adults have brain tumours, and they are more prone to them the older they get.
“In the young, the most common brain cancer is embryonal (it begins in foetal tissue), and in the adults, it is the glioblastoma (aggressively malignant tumours arising from the cells that make up the supportive tissue of the brain),” says Dreyer.
Brain tumours are graded from one to four, with grade one and two being benign or slow developing, and grades three and four more rapidly progressing. Grade four is the most aggressive.
The specialists who remove brain tumours are neurosurgeons, and over many years of clinical practice, Tshwane neurosurgeon Edward Gurnell has seen an increase in malignant brain tumours in his patients.
“This applies to primary brain tumours, those that originate within the brain, and secondary or metastatic tumours, which are tumours that have spread to the brain from elsewhere, such as the lung or breast,” he says.
“It’s important to note in the case of secondary brain tumours, however, that cancer patients are surviving longer with modern-day chemotherapy treatment, and therefore a greater number of patients develop secondary brain deposits (of cancerous cells).”
The causes of brain tumours – benign or malignant – are mostly unknown, and despite a contentious Roman court finding recently that there is a “causal link” between cellphone use and brain tumours, and singer Sheryl Crow’s belief that her benign brain tumour was caused by excessive use of her cellphone, there is no supporting scientific evidence.
The most common symptoms are headache, nausea, vomiting, epileptic seizures or neurological deficits, like partial paralysis of the face, says Gurnell.
Cape Town neurosurgeon Roger Melvill says the “insidious nature” of brain tumour symptoms means the correct diagnosis is often delayed, and a slow-growing tumour such as a meningioma (forms on the brain’s surface membrane and not in the brain itself) can go undetected for years.
“The tumour may be in an area where the risk of loss of sight or speech ability, say, is too high. So the surgeon’s call might be to leave it,” says Melvill. “Ideally, however, as much of the tumour as possible is removed.”
Surgical removal is also the mainstay treatment of benign tumours, as they may be causing pressure inside the brain, disturbance of brain function or abnormal brain activity like epilepsy.
Dave Chambers, a Cape-based editor who was diagnosed with a table tennis ball-sized meningioma in 2003, says his first symptom was a seizure in his sleep.
“I was having convulsions and biting my tongue,” he recalls.
His wife called an ambulance and a tumour was soon found by an MRI scan. After it was successfully removed, Chambers went on epilepsy treatment for a year and must undergo an MRI scan every five years to check that the tumour hasn’t grown back.
In the case of tumours affecting brain function, neurosurgeons sometimes rely on a technique called “awake cortical mapping”, which allows the surgeon to “wake” the patient during the surgery to test, say, language function using delicate electrical stimulation.
“The brain doesn’t feel pain, so this is a very useful technique,” says Melvill.
For malignant tumours, radiotherapy – sometimes combined with chemotherapy – is the standard follow-up treatment after surgery, but the recovery rate depends entirely on the unique nature of the tumour and how rapidly it grows back.
“For malignant tumours, there is no cure, only control of tumour growth and delaying a recurrence of the tumour,” says Gurnell.
The tumours with the poorest prognosis for survival are the glioblastomas, adds Melvill.
Andrew Lanham, who had resigned himself to an early death more than once during the trauma he experienced, says: “It’s not necessarily a death sentence. In fact, surviving one makes you appreciate your life more.” - Pretoria News