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