Cancer pathology Flashcards
Give examples of benign tumours
Papilloma Gliomata Adenoma Leiomyoma Lipoma
Possible damaging effects of benign tumours
Bleeding Pressure (on other structures) Endocrine toxicity (large amounts of hormones in a non-feedback type manner) Possible progression into malignancy
Examples of malignant tumours
Squamous cell carcinoma
Adenocarcinoma
What are leiomyomas? Discuss their growth
Smooth muscle tumours of the uterus
Increase rapidly in size during pregnancy
Cease growing or atrophy and become largely fibrocalcific after menopause
What is an adenoma?
A benign tumour of epithelial tissue with glandular origin, glandular characteristics, or both (e.g. can grow from adrenal glands, pituitary, thyroid, etc or growing from non-glandular tissue with glandular properties e.g. familial polyposis coli)
What are adenomas called when they transform and become benign?
Adenocarcinomas (most do not transform)
What is a papilloma? Describe it.
A benign epithelial tumour
- grows in a ‘nipple-like’ way
What is a gliomata?
- can be malignant or benign
- tumour of glial tissue of nervous system
What is a lipoma? Describe
Benign. tumour of adipose tissue
- not necessarily hereditary, although hereditary conditions, such as familial multiple lipomatosis, may induce development
What are sarcomas? Give some examples
Malignant neoplasms arising in mesenchymal tissue
- fibrosarcoma - cancer of fibrous origin
- chrondrosarcoma - malignant neoplasm composed of chondrocytes
What are carcinomas? Give examples
Malignant neoplasms of epithelial cell origin (can be derived from all germ layers):
- squamous cell carcinoma - tumour cells resemble stratified squamous cell epithelium
- adenocarcinoma - starts in mucus-producing glandular cells of the body
Example of adenoma
Colonic polyps
What are the characteristics of malignant tumours?
- invasion
- metastasis
- progression
- aberrent differentiation
- pleomorphism (different types of cell)
- anaplasia (poor differentiation)
What are the 6 original Hallmarks?
- Evasion of apoptosis
- Self-sufficiency in growth signals
- insensitivity to anti-growth signals
- sustained angiogenesis
- limitless replicative potential
- tissue evasion and metastasis
What two new hallmarks of cancer were added in 2011?
- deregulating cellular energetics
- avoiding immune destruction
What two new enabling characteristics were added in 2011 to the hallmarks?
- Genome instability
- Tumour-promoting inflammation
What does the 2011 Hallmarks of cancer review focus a lot on?
- role of non-tumour stromal cells in determining the tumour microenvironment
What are the steps of metastasis?
- EMT
- Invasion - breakdown of the ECM and migration
- Establishment of pre-metastatic niche
- Extravasation
- Angiogenesis
What does EMT result in?
Spindle-shaped cells with a strong migratory potential
Give an example of how EMT may occur
- Activation of Snail and Slug occurs via Ras-MAPK pathway
- Activation of any of this pathway leads to loss of E-cad and EMT
What occurs after the cells have acquired the ability to migrate?
- invasion of surround tissue
- breakdown the basement membrane and access blood vessels
What is one of the mechanisms allowing invasiveness? Explain it
Reciprocal interactions between the tumour cells and the surrounding stromal cells
- tumour cells drive stromal proliferation through production of substances (such as CSF1 which drives macrophages)
- The macrophages the produce substances that act on tumour cells (e.g. EGF) → stimulates tumour cell proliferation
What do interactions between stromal cells and tumour cells produce?
A local inflammatory environment → results in the production of enzymes that cause breakdown of ECM and basement membrane
- e.g. matrix metalloproteinase 2
What is the second mechanism that allows invasesiveness?
Active locomotion
Describe active locomotion
- involves manipulation of the internal machinery of their cytoskeleton
- this can be altered by interactions on the cell surface
- MMP cleavage of certain substances in the ECM can generate fragments that bind to cell surface receptors which in turn promote migration
Describe the establishment of pre-metastatic niche
- once the tumour cells have migrated through the tissue & basement membrane, the can enter the blood of lymph vessels and establish new tumour sites
- often depends on blood flow patterns, although it cannot depend solely on this (e.g. kidney is a large recipient of blood but an uncommon site of metastasis)
Describe the ‘seed and soil’ theory
Paget hypothesized it:
- metastatic spread is determined not only by viable tumour cells accessing the site (the seed) but also by a ‘fertile environment’ at the site (the soil) which enables the tumour cell to grow
What is a pre-metastatic niche?
A tumour can create its own ‘soil’ to colonise
How may a primary tumour form a pre-metastatic niche?
- secretion of cytokines to recruit non-cancerious cells to the future metastatic site (incl. endothelial progenitors and haematopoetic cells) → these can form an environment of survivak molecules
- secrete exosomes → these express integrins
What is extravasion?
LEAVING the circulation
Describe non-molecular mechanism of extravasion
- initially does not involve any molecular mechanisms → impact of tumour cells lodging in a capillary bed = damage to the endothelium = exposes basement membrane and allows cells to adhere = access to tissue
Describe molecular mechanisms of extravasion
- important in homing to their correct metastatic site though selection expression of ligands only on target organs
- chemokine action