May 10, 2018–It is well known that environmental mutagens are associated with increased cancer risk. However, why cancers of different tissues tend to have their own specific collections of mutations remains unanswered. In a paper published in Nature Communications, Temko et al. from Benjamin Schuster-Böckler’s group in Ludwig Oxford have found that whilst mutational processes influence the spectrum of mutations in a cancer, the subsequent selection of certain mutations that give the cancer cell an advantage is also required to give the observed signatures.