In 2007 there were 4,676 new cases of brain or central nervous system cancers diagnosed in the UK and around 3,920 non-invasive brain and other CNS tumours were also registered. Despite these numbers less than 1% of all money spent on cancer research in the UK is spent on brain cancer.
Research funded by AICR at the University of Geneva, Switzerland, has revealed why most brain cancers are not attacked and killed by our immune system. Several years ago we awarded a research grant worth £169,862 to Dr Paul Walker to study the immune reaction to early gliomas – the most common type of brain cancer.
Our immune system is able to recognise foreign molecules – including toxins and molecules on viruses – and attack them. Since most cancer cells have some form of different molecules on their surfaces, the immune system should recognise these as foreign and attack them as well. This has been found to happen with some cancers, but not in the case of gliomas. By studying mice that developed gliomas, Dr Walker was able to analyse the very early stages of the tumour and how the immune system reacted to it.
“We analysed the numbers and types of white blood cells in the brain tumours,” explained Dr Walker, “and found there was a very big difference between the early stages of these cancers and later stages. The white blood cells are the cells of the immune system. Some types of white blood cells do the recognising, others do the attacking and others control whether or not the immune system is active. In the early brain tumours we found a very high level of a type of white blood cell that suppressed the immune system, preventing it from attacking the cancer cells when they were small and easiest to destroy.”
Possibly the most interesting part of their research was when they discovered that the immune system was not totally incapable of attacking glioma cells. By vaccinating the mice against glioma cells they could stimulate the white blood cells to recognise and fight these cancer cells. This holds out the hope that, in future, it may be possible to treat or prevent brain tumours in people by some form of vaccination.