More recently, the recognition of the role of stem cells in epithelial homeostasis and the development of cancer stem cells was included in this concept of field cancerization: mutated stem cells, with mutations that confer growth advantages (such as in the TP53 and NOTCH family genes), lead to the expansion of these mutated clones, with the formation of a mutated patch and, afterwards, a mutated field, where the addition of further genetic alterations leads to dysplasia, carcinoma in situ, and invasive and metastasizing carcinoma [28,36,37]. The gene discussed is TP53; the disease is cancer.