The term precancer, although not entirely accurate, is ingrained and widespread. Clinicians understand by it such local changes in tissues and organs that predispose to the development of cancer and prepare the ground for its occurrence. Everyday clinical observations and numerous experiments confirm such a generally accepted view, which does not exclude, however, the possibility of tumor development even without precancerous changes. The latter is difficult to prove, but it must be admitted in the absence of any indications in the anamnesis in adults, and especially in young people.