Download Cancer

Cancer progresses through
accumulation of multiple mutations
Each successive mutation allows those cells to
proliferate more quickly than those around it.
Cancer is a genetic disease,
but not usually inherited.
• Most cells in the
body are somatic
cells.
• Most mutations
are in the
somatic cells.
• Germline
mutations are
inherited by
offspring
…but it sometimes is inherited and
runs in families.
• Each cell has 2
copies of each
tumor
suppressor gene.
• Both copies must
be mutated for
cancer to form.
• If first mutation
is inherited, all
cells are
susceptible to
2nd mutation.
2-hits in retinoblastoma
• Cancer of the retina
• Small tissue with only one tumor suppressor gene
active.
• Most people get only 1 mutation in any given cell
– No cancer
• Some people get 2 mutations in any given cell
– Cancer in one eye
• Some people inherit mutation in all of their cells.
Next mutation causes cancer.
– Cancer in both eyes usually by age 5.
What causes mutations to
occur and spread?
• Mutations may be inherited
• Carcinogens – any agent involved in the
promotion of cancer
–
–
–
–
–
–
–
Smoke (esp. cigarette smoke)
Radiation / sun
Chemicals / solvents
Infectious diseases (eg Human papillomavirus)
Food (esp. charred meat)
Hormones (eg. Estrogen)
Many, many others!
•
External signals that control cell
proliferation:
growth
factors
Growth
Factors: A protein
released
by certain
cells that stimulates other cells to divide
External signals that control cell proliferation
Cell proliferation: tumors recruit blood
vessels to supply oxygen and nutrients.
Tumors secrete Growth factors that promote
angiogenesis (formation of blood vessels
Tumor growth
First
mutation
causes rapid
growth
2nd mutation
increases growth
rate and changes
appearance of
cells
After recruiting blood
supply, may
metastasize to other
tissues
Major Types of Cancer
• Carcinoma – external
or internal body
linings
• Sarcoma – supportive
tissue (muscle or
bone)
• Leukemia – blood or
blood-forming tissue
• Lymphoma – lymph
system
• Family history
Risk Factors
– But only 5% of cancers are inherited
• Tobacco use
– 30% of all cancers and 87% of lung cancer
• Smokeless tobacco
– Oral and pancreatic cancers
• Diet
– Eat fruits and vegetables
– Avoid charred meats
– Avoid preserved meats
Risk factors
• Being sedentary
– Moving helps push food through your intestines,
limiting exposure to carcinogens
• Alcohol
• Irregular medical care
– Cancer goes undetected
• Sunlight (UV and other radiation)
• Chemical carcinogen exposure
• Infectious agents (eg. HPV for cervical cancer)
Treatment options
• Surgery
• Removal of cancerous tissue
• Radiation
• Kills cancer cells (usually targeted to specific tissue)
• Chemotherapy
• Uses chemicals to kill cancer cells (throughout body)
• Biological immunotherapy
• Strengthens immune system
• Transplants
• Particularly Bone Marrow for leukemias