A proposed model of cancer as the inappropriate expression of non-body introns.

An a posteriori proposal is made that cancer represents an alien non-body phenotype erupting from "silent" gene groups within actively coding regions of a normal cell's genome. Relevant empirical data is garnered from the literature and twelve premises are derived from the data. On the basis of these premises it is hypothesized that the malignant neoplastic phenotype results from interference with non-histone chromosomal proteins causing retention and expression in a body cell of non-body introns. These are asserted to be the same introns which, as exons in a trophoblast cell, direct the normal development of the fetal placenta. Development of a malignant tumor is presented as a pathological recapitulation of the development of a normal placenta. Unrestrained tumor growth is attributed to the inability of endogenous body chalones to suppress the non-body gene groups coding for neoplastic mitosis, while invasion and metastasis result from failure of the non-body genes which code for implantation and mitosis to switch off at the proper time. The hypothesis asserts that all carcinogenic agents alter phosphorylation of non-histone chromosomal proteins, that cancer and normal trophoblast cells are genetically programmed to travel through the body's vascular system to effect immunosuppression in lymphoid tissues, that malignant neoplastic tissue will regress when exposed to trophoblast-based chalones, and that mammals immunized against trophoblast-based antigen will be resistant to the development of malignant tumors.