What Is Cancer?
Cancerous cells display uncontrolled growth (that is, they start dividing beyond normal limits). The rate of division is faster in some cancers than in others, but in all cancers, the cells never stop dividing: they have infinite lifespans. They invade neighboring tissues, and they may metastasize (spread to distant parts of the body).
Cancer TumorsCancerous cells form a tumor, or mass, although some (like leukemia) do not. Tumors may be benign or malignant.
- Benign tumors don’t destroy neighboring tissues, don’t spread throughout the body, and stop growing before they become very large. Moles and warts are benign tumors.
- Malignant tumors invade adjacent tissues, metastasize throughout the body, and never stop growing.
Critical to the growth of malignant tumors is angiogenesis, the formation of new blood vessels. Malignant tumors have the ability to produce activator molecules, such as vascular endothelial growth factor. Activator molecules induce the formation of new blood vessels to supply the tumor, allowing for cell reproduction and tumor growth.
Photo attribution of crab illustration
Copyright 2007 Pearson Scott Foresman