In this video Dr. Sarah McClelland a post-doc in Prof. Charles Swanton Lab at Cancer Research UK, discusses her work investigating chromosomal instability in cancer. Until recently it was thought that chromosomal instability was primarily caused by errors that occur during mitosis. However, Sarah’s work demonstrates that chromosomal instability can arise as a result of errors that occur during DNA replication. Sarah tells SelectScience how her laboratory has identified three genes which can cause chromosomal instability. This work, which was recently published in nature with lead co-author Dr. Rebecca Burrell, has huge implications for new therapeutic approaches to limit intratumour heterogeneity.