A. Characterization of cancer

Uncontrolled cell division, but critical difference is these cells are capable of spreading throughout the body and invading other tissues, a process known as metastasis. In most cases the dividing cells are clumped together as a tumor, although this is not true in all cases (leukemia). Benign tumors do not metastasize (remain enclosed by connective tissue). Malignant tumors do metastasize -- clumps of cancerous cells break off and enter blood or lymphatic system and initiate a new tumor elsewhere.

B. Traits of cancer cells

1. No contact inhibition of cell division (normal cells cease dividing once they contact other cells)

2. No anchorage dependency (normal cells must contact some substrate to divide), thus cancer cells can divide in liquid

3. No requirement for serum growth factor (normal cells require this)

4. Failure to differentiate -- stay immature, thus no useful function

C. What is involved in metastasis?

1. Cells break loose from tumor

2. Cells gain access to blood or lymphatic system

3. Cells escape being destroyed by white blood cells

4. Cells leave circulation and locate in some new tissue

5. New tumor indices growth of new blood vessels to it for nourishment

D. Causes of cancer

1. Gene mutation that causes uncontrolled growth and cell division (normal protooncogene mutates to abnormal oncogene)

2. Mutation of gene that normally suppresses the development of cancer cells and tumors

3. The above (1 and 2) may be initiated by environmental agents or pathogens

E. Treatment of Cancer

1. Surgery

2. Radiation

3. Chemotherapy

4. Immune System activation

F. Death by Cancer

1. Infection (cancer suppresses immune system)

2. Interference with vital organs (due to growth of tumors)

3. Starvation (the body wastes away; vital resources nourish the cancer)

4. Hemorrhage (internal bleeding, tumor interferes with blood vessels)