Cancer genes differ in different parts of a tumor

Taking a sample from just one part of a tumor may not give a full picture of its ‘genetic landscape’, according to a landmark study published in the New England Journal of Medicine. The findings could help explain why attempts at using single biopsies to identify biomarkers that can be targeted with personalized cancer treatments can be targeted have not been more successful. Cancer Research UK scientists carried out the first ever genome-wide analysis of the genetic variation between different regions of the same tumor using kidney cancer samples. They found that the majority, around two thirds of gene faults, were not shared across other biopsies from the same tumor. By analysing the location of shared mutations in relation to the whole tumor, the researchers were able to trace the origins of particular subtypes of cancer cells back to key driver mutations. This allowed the scientists to create a ‘map’ of how the pattern of faults within the tumor might have evolved over time.