It is well established that cancer is a genetic disease. It is the result of an accumulation of changes (mutations) in genes that control cell division. The actual order in which the mutations occur is not clear. Research from the University of California was able to determine the order of genetic changes in two different cancers (squamous cell carcinoma and ovarian cancer). Their results shed new light on the role of the p53 tumor suppressor gene in cancer development and have important implications on the early detection and diagnosis of cancer.