Transcript Cancer - HRSBSTAFF Home Page

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:
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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:
1. Invasion: a cancerous cell manages to move
throughout the body using the blood destroying
healthy tissue in a process
2. Angiogenesis: the cancer cell manages to divide and
new blood vessels grow to supply it with blood
3. Metastasis: when a tumour successfully spreads to
other parts of the body, grows, invading and
destroying other healthy tissues
Clip showing angiogenesis:
http://www.medicalnewstoday.com/info/canceroncology/
How is cancer classified?
• There are five broad groups that are used to classify
cancer.
1. Carcinomas: cells that cover internal and external parts
of the body (ex. lung, breast, and colon)
2. Sarcomas: cells that are located in bone, cartilage, fat,
connective tissue, muscle, etc.
3. Lymphomas: cancers that begin in the lymph nodes and
immune system.
4. Leukemias: cancers that begin in the bone marrow and
often accumulate in the bloodstream.
5. 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.
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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
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To do:
• Read page 100-102
• Complete practise questions 1, 2, 3
• Complete Section 3.5 questions 1, 2