This phenomenon is known as the concept of “field cancerization” or “a field for cancerization”.43–45 The concept was first proposed by Slaughter et al. based upon the presence of multiple microscopic cancers in grossly normal mucosa of patients with oral squamous carcinomas.43 The finding was further advanced by detecting TP53 mutations in clonally expanded patches of cells, which may or may not be detected by routine microscopic examination, in multiple types of cancers (Fig. 2c). The gene discussed is TP53; the disease is cancer.