2. Cancer Uncontrolled Cell Division

3. Causes of Cancer Genetics Spontaneous mutation Stress Chemical carcinogens Radiation Most cancers result from avoidable combinations of environmental causes

4. 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

5. 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

6. 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)

7. http://www.hhmi.org/biointeractive/medi a/angiogenesis-lg.mov http://www.hhmi.org/biointeractive/medi a/angiogenesis-lg.mov