Different cancers go through the same genetic changes during their development, according to new research.
In a recent study, researchers from the Francis Crick Institute, London, and the University College London (UCL) Cancer Institute found that there are similarities between the way different cancers acquire chromosomal changes and evolve. The findings may help to predict the way a patient's cancer develops, which could enable new treatment strategies.
'The presence of common changes supports the theory that there are a number of genetic pathways through which tumours must evolve,' remarked Professor Charles Swanton, senior author and group leader at both the Francis Crick Institute and at UCL. 'Identifying these would move us a step closer to writing cancer's evolutionary rule book,' he added.
The study, published in Nature, examined the genetic make-up of 1421 samples from 394 patients, spanning 22 different cancer types. The researchers used a technique developed with collaborators at the Max Delbruck Centre for Molecular Medicine in Berlin, Germany to analyse the samples.
The analysis revealed that even across different cancer types, tumour cells were likely to undergo the same genetic changes in their chromosomes at particular timepoints in their development – some mutations were common at the beginning of tumour development, whereas others were more prevalent in later stages. Common mutations across different cancers included those that could aid tumour growth, by helping, for example, to evade the immune system or survive in low oxygen conditions.
In a tumour, cancerous cells divide rapidly, and in doing so make copies of their DNA. This copying is error-prone and may lead to genetic mutations including chromosomal changes. As a result, distinct sub-populations (subclones) of cells evolve with different characteristics. Rather than developing randomly, the study showed that the sub-populations independently acquired the same mutations to their chromosomes. Evidence of this so-called 'parallel evolution' was found in 37 percent of patient tumours (146 patients) as part of the study.
Thomas Watkins, lead author and PhD student at the Francis Crick Institute, explained: 'In a tumour there are lots of genetic changes taking place. The fact we saw similar chromosomal changes take hold independently within a tumour in separate subclones suggests these changes are important for the tumour'.
Dr Nicholas McGranahan, joint corresponding author and group leader at the UCL Cancer Institute, commented on the importance of finding patterns in cancer development pathways. Speaking of the seeming 'chaos' of chromosomal changes, he said: 'Of course, if you could predict them, this opens the door to scientists and doctors developing new treatments, or roadblocks, which could block these evolutionary pathways.'