THE GENESIS OF TUMOURS — MUTATION OR ABNORMAL DIFFERENTIATION?

Although first proposed by Boveri as long ago as 1914 (Weinstein, 1970), the concept of somatic mutation still underlies most theories of the nature and causation of tumours, and the assumption that tumours are composed of clones of genetically altered cells (Burnet, 1973) forms the basis of most forms of non‐surgical therapeutic attack, especially by physical, chemical and immunological means. So well entrenched is this concept that it has rarely been seriously challenged, yet the pathologist who has daily to diagnose and assess neoplastic disease sees many aspects of tumours that are hard to explain on this basis. For this reason an attempt to provide an alternative explanation of neoplasia appears justified.