More than a thousand scientists have built the most detailed picture of cancer ever in a landmark study.
They studied nearly 2700 tumours and 38 different types of cancer over a ten-year period.
Dr Michelle Dickinson told Andrew Dickens they've been able to look at the genetic changes over time and backtrack to see if there were any genetic changes which may have started it.
"What they figured out is, actually, it's only about four or five mutations that creates different types of cancer."
The study, published in the journal Nature, could allow treatment to be tailored to each patient's unique tumour, or develop ways of finding cancer earlier.