Malignant transformation is the process by which cells acquire the properties of cancer. This may occur as a primary process in normal tissue, or secondarily as malignant degeneration of a previously existing benign tumor.
There are many causes of primary malignant transformation, or tumorigenesis. The underlying commonality is genetic mutation either by inheritance or more commonly by acquiring mutations in one's DNA over time. Although malignant transformation may occur because of changes within the cell, it can be induced by inorganic toxic substances such as cadmium or arsenite and organics such as tobacco-specific nitrosamines. It is also thought that some malignant transformations are due to viruses such as the Epstein-Barr virus, although this is currently restricted to just a few cancer types. A more common cancer associated with viral infection is cervical cancer, which has been linked to the human papilloma virus.
Malignant transformation of cells in a benign tumor may be detected by pathologic examination of tissues. Often the clinical signs and symptoms are suggestive of a malignant tumor. The physician, during the medical history examination, can find that there have been changes in size or patient sensation and, upon direct examination, that there has been a change in the lesion itself.
Risk assessments can be done and are known for certain types of benign tumor which are known to undergo malignant transformation. One of the better known examples of this phenomenon is the progression of a nevus to melanoma.
Famous quotes containing the word malignant:
“How did you get in the Navy? How did you get on our side? Ah, you ignorant, arrogant, ambitious—keeping sixty two men in prison cause you got a palm tree for the work they did. I don’t know which I hate worse, you or that malignant growth that stands outside your door. How did you ever get command of a ship? I realize in wartime they have to scrape the bottom of the barrel. But where’d they ever scrape you up?”
—Frank S. Nugent (1908–1965)