Radiology, Vol 179, 297-306, Copyright © 1991 by Radiological Society of North America
From chimney sweeps to oncogenes: the quest for the causes of cancer
EJ Hall
Center for Radiological Research, College of Physicians and Surgeons, Columbia University, New York, NY 10032.
Over the past 200 years, a bewildering array of chemical, physical, and
viral agents has been identified that can cause cancer, but the mechanisms
involved are only now becoming clear. In the leukemias and lymphomas, it
appears that the activation of cellular oncogenes is important. The genes
involved are present in all normal cells and are often associated with cell
growth and regulation. When activated, they act in a dominant fashion to
cause a cell to express the malignant phenotype. There is increasing
evidence that in solid tumors, a more important mechanism may be the loss
of a suppressor gene. The classic example is retinoblastoma, in which the
retinoblastoma gene has been cloned and is also found to be associated with
several other common cancers including sarcomas and small cell lung cancer.
It is likely to be one of a family of such genes. It may well be that the
activation of one or more oncogenes or the loss of one or more suppressor
genes, or both, is required for a tumor to progress from initiation through
promotion to a metastasizing malignancy.
