Cancer Physiology; Disease and Symptoms Flashcards
What is cancer? What is it characterised by?
- A GROUP of diseases (many different aetiologies)
- Characterised by abnormal cell growth, where cells may acquire the potential to metastasise from the primary tumour (site of origin) to other sites in the body; secondary tumours
What is tumour growth dependent upon?
- Delivery of nutrients and oxygen via increased vascular supply
- Thus, angiogenesis (initiation of growth of blood vessels towards tumour)
What are the two different types of tumour, and how are they characterised?
Benign:
- Cells well-differentiated (look like normal cells)
- Slow growing
- Encapsulated; cells are self-contained
- Does not metastasise “not trying to escape”
- Can remove via surgery
Malignant:
- Cells poorly differentiated
- Frequent cell division; fast growing
- Loss of capsule
- Capable of intravasation (breaking through any capsule and pushing through, e.g. endothelial lining, travelling around the body via blood vessel), arrest at distant site, metastasis (90% capable of metastasis)
What is a carcinoma?
- Solid tumour, most common type of cancer
- Arising from cells of embryonic endoderm (interior layer, which develops into interior lining of GIT and lungs) or ectoderm (exterior layer, giving rise to epidermis of skin cells, neurons of brain etc.)
- Covers external and internal body surfaces e.g. lung, breast, colon
What is a sarcoma?
- Cancer arising from cells of embryonic mesoderm (middle layer)
- Of the supporting tissues of the body such as bone, cartilage, fat, connective tissue and muscle
- Slightly less common
What is a lymphoma?
- Cancer that arises in the lymph nodes and tissues of the body’s immune system
- Lymph = lymphatic; body’s drainage system, related to the immune system
- “Liquid cancer”
What is a leukaemia?
- Cancer of the immature white blood cells that grow in the bone marrow, and accumulate in large numbers in the blood stream
- “Liquid cancer”
What are some causes of cancer?
- Tobacco
- XS body weight
- Physical activity
- Diet
- Hormones (reproductive factors; late age at first pregnancy is a factor in breast cancer)
- Sunlight (UV radiation)
- Occupational carcinogens (asbestos, benzene, pesticides)
- Infectious agents: viruses (HPV in cervical cancer), bacteria (H. Pylori cause gastric ulcers, sometimes cancer)
- Medical treatment (radio/chemo-therapy increases risk later on)
- Pollution (diesel exhaust, xenoestrogens)
- Genetic factors
What are the symptoms of cancer?
- They are disease-specific
- Often none in early stages; metastases happens v early on, often asymptomatic
What are the typical symptoms of lung cancer?
- Cough haemoptysis (coughing up blood)
- Chest pain
- Breathlessness
- Tiredness
What are the typical symptoms of pancreatic cancer?
- Weight loss
- Stomach/back pain (rule out other back pain sources)
- Jaundice
- Development of diabetes
What are the typical symptoms of breast cancer?
- Lump or thickening (90% of such abnormalities are benign)
- Change in breast size
- Discharge
- Bleeding
- Weight loss
What makes a cell metastatic?
Mutagenic initiation:
> Chemicals, radiation, viruses, spontaneous changes
> Changes that are positively selected
Point mutations:
> Missense, nonsense, or silent
Chromosomal alterations:
> Deletion, insertions, aneuploidy (abnormal normal no. of chromosomes in a cell), translocation
Epigenetic alterations (nongenetic influences on gene expression): > Acetylation, methylation
What are the properties of metastatic cells?
- Local invasion into vasculature
- Survival in a blood vessel
- Arrest at distant site (integrins)
- Extravasation
- Growth of secondary tumour, angiogenesis.
What things allow metastatic cells to invade the vasculature?
- Loss of cell adhesion; cadherins normally keep endothelial wall of vasculature nice and tight
- Gain of alternate adhesion; integrins, allows cancer cells to cling on to outside of vessel (at secondary site?)
