title: The trophoblast theory of cancer (John Beard, 1857-1924) revisited.
abstract: Beard's theory can be restated in a modified form in modern terms in the following way. Cancer represents primarily trophoblastic tissue derived either from an aberrant germ cell or from a somatic cell whose normally repressed 'asexual generation' genes are abnormally reactivated ('derepressed'). The variety of tumors, other than teratomas, may be due to a parallel chance derepression of some genes of somatic ('sexual gneration') characters. This would be a defensive reaction against intramural parasitization by trophoblast and would result in the differentiation and hyperplasia of normally present more primative somatic cells.
mesh_terms: D004626:Embryology / Q000266:history*; D005854:Germ Cells; D049673:History, 20th Century; D006801:Humans; D009369:Neoplasms / Q000196:embryology / Q000209:etiology*; D012606:Scotland; D014327:Trophoblasts; D015046:Zoology / Q000266:history