Classic view on cancer
The classic image of a tumour is a collection of cells, each of which is capable of developing into a new lump. In other words, the driving force behind a tumour is the tumour itself. In practice, though, AMC researchers see something different. When they inject a bowel cancer cell into a mouse, for example, nothing happens. At least a million cells are needed before a tumour actually forms.

Alternative hypothesis
An alternative hypothesis is now gaining ground: only one particular type of cell – the cancer stem cell – is responsible for a tumour’s growth and spread. Studies on laboratory animals in recent years have lent weight to this theory. But according to supporters of the traditional hypothesis, that evidence is based on xenotransplantation, that is, the transfer of human cancer cells to a mouse. Unknown processes may well be playing a role here. It is a valid argument. A new mouse that is suffering from human bowel cancer should resolve the matter within the next few years. Another way of looking at cancer is through gene expression in tumour tissue. Particularly active genes are probably oncogenous, whereas inactivity may indicate an inhibiting function. Microarrays are now being used to analyse gene expression in bowel tumours and their precursors. This technique also has an important role to play in research into neuroblastoma.

‘Smarter’ therapies
A neuroblastoma is a type of tumour that is found mainly in young children. In some patients they disappear spontaneously, whilst others are beyond treatment. An intensive molecular biological hunt for potential oncogenes should eventually result in ‘smarter’ therapies, particularly for aggressive neuroblastomas, which are currently almost impossible to cure. In general, the outlook for children with cancer is constantly improving: about 75 per cent are now cured. Despite this, however, there are good reasons to keep monitoring even after recovery. Many suffer physical or psychological problems in later life as a result of their treatment. Researchers associated with PLEK (the AMC’s clinic for the later effects of childhood cancer) are playing a leading role in tracking these problems.