What are the 4 main characteristics of malignant cancer cells?
- Reproduce despite normal constraints that inhibit cell proliferation and clonal expansion
- Cancer cells invade and colonise territories normally reserved for other cells
- Cancer cells are clonal in nature i.e. daughter cells inherit properties of the mother cell
- Cancer cells have undergone cell transformation from normal cells and thus have different histology and pathology
Does the outcome and prognosis of the cancer depend on the cell type of origin and the tissue of origin?
- Yes
Are all cancers a single disease?
- No
What can bring on unregulated cell growth?
- Uncontrolled cell proliferation
- A lack of apoptosis
What causes cancer?
An accumulation of genetic mutations that confer a survival advantage to the cancer cell e.g. increased cell growth, altered tissue invasiveness, resistance to apoptosis
What is the difference between a benign and malignant tumour?
Benign:
- Appear under microscope like the tissues they came from
- Remain localised and do not spread
- Usually do not cause problems unless they grow in a confined space i.e. the brain
Malignant:
- Do not resemble the tissue or cell of origin
- Often have irregular structures, large variable nucleus, little cytoplasm, evidence of mitosis, little specialised structures
- Invade surrounding tissues
What histology/pathology is observed in cancer cells?
- An enlarged nucleus
- Changes to the cytoskeleton
- Loss of specialised features
What are the two sources of genetic mutations causing cancer?
- Inherited mutations (germ line errors)
- affects every cell in the body - Acquired mutations (somatic errors)
- only cancer cells carry the mutation
Which cells of the body are most susceptible to DNA damage?
- Rapidly dividing cells are particularly susceptible to genetic damage and cancer
- In somatic cells that divide frequently e.g. bone marrow, gut cells, skin cells etc. carcinogens cause DNA damage causing mutation of one base to another
- There is less time for DNA repair enzymes to repair these errors in rapidly dividing cells
What is an inherited cancer predisposition syndrome?
- About 10% of all cancers result from inheritance of a mutated gene that predisposes the individual to cancer
- Inherited susceptibility genes are identified for many forms of cancer
- In many cases however the genetic predisposition must be combined with the appropriate environmental stimulus for cancer to develop
Can cancer susceptibility syndromes be heterogenous?
Yes, there are a number of genes that when abnormal can lead to a similar phenotype
What is metastasis?
- The spread of cancer cells from one tissue to another part of the body
What are the stages of metastasis:
- Break through the basal lamina to invade local tissues and vessels (extraceullular matrix degradation)
- Cancerous cells enter capillaries or vessels (intravasion)
- Tumour cell migration
- Altered tumour cell adhesion in distant capillary beds/tissues (extravasion)
- Altered tumour cell proliferation
- Tumour cell survival 7. angiogenesis
