Cancer: Uncontrolled Cell Division Biology 12

Some Stats from WHO: Cancer is a leading cause of death group worldwide and accounted for 7.4 million deaths (around 13% of all deaths) in 2004. The main types of cancer are: Lung (1.3 million deaths/year) Stomach (803,000 deaths) Colorectal (639,000 deaths) Liver (610,000 deaths) Breast (519,000 deaths)

What is cancer? Cancer is a class of diseases characterized by out-of-control cell growth. There are over 100 different types of cancer and each is classified by the type of cell that is initially affected.

What cause cancer at the cellular level? Cancer is ultimately the result of cells that uncontrollably grow and do not die, normal cells in the body follow an orderly path of growth, division, and death. Programmed cell death is called apoptosis, and when this process breaks down, cancer begins to form. Unlike regular cells, cancer cells do not experience programmatic death and instead continue to grow and divide. This leads to a mass of abnormal cells that grows out of control.

How is a cancer cell different from a normal cell? Larger then normal nuclei (and/or multiple nuclei) Small cytoplasm Can grow in isolation from other cells Do not “stick” to the cells around them They may have abnormal numbers and types of chromosomes caused by mutations

What causes the mutations that lead to cancer? Viruses (ex. HPV --> cervical cancer) Bacteria (ex. H. pylori --> gastric cancer) Chemicals (ex. Cigarette smoke --> lung cancer) UV and ionizing radiation (ex. skin cancer)

What can happen after a cancer cell forms: Invasion: a cancerous cell manages to move throughout the body using the blood destroying healthy tissue in a process Angiogenesis: the cancer cell manages to divide and new blood vessels grow to supply it with blood Metastasis: when a tumour successfully spreads to other parts of the body, grows, invades and destroyes other healthy tissues Clip showing angiogenesis: http://www.medicalnewstoday.com/info/cancer- oncology/

How is cancer classified? There are five broad groups that are used to classify cancer. Carcinomas: cells that cover internal and external parts of the body (ex. lung, breast, and colon) Sarcomas: cells that are located in bone, cartilage, fat, connective tissue, muscle, etc. Lymphomas: cancers that begin in the lymph nodes and immune system. Leukemias: cancers that begin in the bone marrow and often accumulate in the bloodstream. Adenomas: cancers that arise in the thyroid, the pituitary gland, the adrenal gland, and other glandular tissues.

How is cancer treated? Depends on the type of cancer, the stage of the cancer (how much it has spread), age, health status, etc. Surgery Radiation Chemotherapy Immunotherapy Hormone therapy Gene therapy

Cancer in Plants: Not exclusive to humans Plant galls are abnormal outgrowths of plant tissues and can be caused by various parasites, from fungi and bacteria, to insects and mites.

Cancer in Dinosaurs too? Many dinosaurs had cancer, researchers have discovered. Their tumours were like those of human patients, showing that cancer has been around for a very long time. "Diseases look the same independent of what critter is affected," says radiologist Bruce Rothschild of the North Eastern Ohio Universities College of Medicine in Rootstown http://www.guardian.co.uk/science/2003/oct/23/dino saurs.science

Animation: http://www.youtube.com/watch?v=qxcFbqA7w 80

To do: Read page 100-102 Complete practise questions 1, 2, 3 Complete Section 3.5 questions 1, 2