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Cancer
Uncontrolled Cell Division
Causes of Cancer Genetics Spontaneous mutation Stress Chemical carcinogens Radiation
Most cancers result from avoidable combinations of environmental causes
Properties of Cancer Cells
They reproduce in defiance of the normal restraints
They don’t stop at the checkpoints in the cell cycle
They lack cell-to-cell adhesion (contact inhibition) signals
They resist to cell “suicide” signals (apoptosis)
They form a tumor (neoplasm) They invade and colonize
territories normally reserved for other cells
They quickly alternate shape between round and elongated
Formation of a Tumor
Mutation and initial mild disorder of cell behaviour cause a normally dividing cell to divide erratically
As the abnormally dividing cells form the tumor, they stimulate the development of blood vessels (angiogenesis) for oxygen and nutrients
Benign versus Malignant Tumors
Benign: cells of the tumor remain clustered together
Malignant: cells of the tumor break lose, enter the bloodstream or lymphatic vessels and form secondary tumors (metastases)
http://www.hhmi.org/biointeractive/media/angiogenesis-lg.mov