Cancer Flashcards
Adenocarcinoma:
cancer arising from ductal or glandular structures
Anaplasia
absence of differentiation
Cancer
refers to a malignant tumor and is not a term used to refer to benign growths
Carcinogens
are substances that, when introduced into a cell, cause changes in the
structure and function of the cell that lead to cancer.
Carcinogenesis
production of cancer
Carcinoma
cancer arising from epithelial tissue
Leukaemia
Cancers from blood forming cells
Oncogene
Derived from a mutated porto-oncogene which now results in excessive and uncontrolled cell growth
Proto-oncogene
Normal gene that promotes cell growth
Sarcoma
Cancer from connective tissue
Tumour suppressor gene
Inhibits cell replication
What are the characteristics of benign neoplasms?
Resemble normal cells, don’t infiltrate, grow slowly, don’t metastasize, don’t recur after removal, localized issue, doesn’t cause tissue damage, and don’t cause death
What are the characteristics of malignant neoplasms?
- cells often bear little
resemblance to the normal
cells of the tissue - infiltrates and destroys the
surrounding tissue - rapidly growing
- gains access to blood lymph to make mets
- tends to recur when removed
- generalized effects: anemia, fatigue, weightloss
- causes death and tissue damage
What are the 3 basic units of DNA that make up nucleotides?
- Pentose sugar molecule (deoxyribose)
- Phosphate molecule
- Nitrogenous bases
What is the codon?
The protein coding DNA = are successive triplets of bases
What is the malignant transformation of cells?
An accumulation of mutations in a particular class of genes
What are the 2 gene classes that when mutated account for most controlled cell proliferation seen in cancer?
- Proto-oncogenes
- Tumour suppressor genes
What are the characteristics of cancer cells?
- Loose shape and boundaries
- Stop responding to growth-inhibiting signals
- Replicate uncontrollably
What does a tumor descend from?
A single precursor cell that has been transformed
What other carcinogens are hits that can cause normal cells to mutate?
- Hormonal
- Viral
- Occupational
- Environmental
- Behavioural
- Other/random
What are the 4 types of gene mutations that can occur to result in cancer?
- Point mutation
- Chromosome translocation
- Gene amplification
- Frame-shift mutation
What is a point mutation?
A single change to one base group?
What is a frame shift mutation?
a) An addition is added into a base group resulting in an inappropriate number of bases, no longer in triplets
b) OR a deletion occurred which makes it an inappropriate number of triplets
What is chromosome translocation?
A piece of one chromosome that is relocated to or swapped with a different part of the chromosome
What is an example of chromosome translocation?
Burkett’s lymphoma (B cell cancer)
- Ig gene on chromosome 14 and MYC photo-oncogene on chromosome 8 are swapped
This results in HIGH rate of B cell proliferation
=
Increase chance of transcription error and development of cancer
What is gene application?
Over-expression or duplication of a piece of chromosome
What is an example of gene amplification?
Breast cancer: Human epidermal growth factor 2(HER-2) gene becomes over expressed
=
cells in breast ducts grow and replicate outside of their normal boundaries
What 3 factors contribute to gene mutation?
- Hereditary genetic error
- Exposure to carcinogen
- Exposure to a virus
What is a hereditary genetic error and what are the 2 types?
An inheritance of altered gene from parent that passes on an increased risk but not guarantee of developing cancer
- Autosomal dominant
- Autosomal recessive
What is autosomal dominant inheritance?
NO carriers, only one copy of allele is mutated for condition to result.
Gender dependent
What is autosomal recessive inheritance?
Person can be a carrier and not be affected
What are examples of viruses that can cause genetic mutations?
- Epstein Barr - burrito’s lymphoma
- HPV - cervical
- Hep B - liver
- Human T-cell leukaemia virus
What are the two basic control systems to prevent a single cell from becoming cancer?
- Promotion of cell growth
- Safeguard systems`
Describe the “promoting cell growth” system and what happens when it fails?
Proto-oncgenes are normal genes that encode proteins for cell growth and development
Damage or mutation of these genes results in ONCOGENES which flood cells to keep mutating inappropriately
What are the 4 safeguard systems that help prevent a single transformed cell from becoming cancer?
- Tumour suppressor gene
- Mismatch repair gene
- Apoptosis
- Immune system
Describe what occurs with the inactivation with the TSG
Tumour suppressor gene normally inhibits cells growth
Inactivation or damage prevents inappropriate cell growth
*TSG is a recessive gene
What happens when the mismatch repair gene is inactivated?
Mismatch repair gene usually reads DNA sequences and repairs errors from replication
If this gets damaged/doens’t occur, errors don’t get fixed = mutation
What happens when apoptosis fails?
Normal cell remove doesn’t occur and old damaged cells are allowed to continue replicating
What happens with immune system dysfunction?
Cancer cell replication outpaces the immune system
Cancer cells will change their appearance and display self antigens
Cancer cells lose contact inhibition and start growing all wacky
What 3 factors influence the local manifestations of cancer?
- Location of the tumour
- Size and distend ability of the space the tumour is occupying
- Surrounding structures
What affects systemic manifestation of cancer?
- If the cancer is a systemic or local type
- Is a local type metastasized
5 Steps of tumour spread
- Transformation of cell
- Growth of transformed cell
- Local invasion (mechanical pressure, lytic enzymes, motility)
- Dissemination into lymphatics and bloodstream
- Metastasis
What happens during the transformation of an individual cell during tumour spread?
Individual cell undergoes mutation
Explain the growth of the transformed cell step of tumour spread
The transformed cell starts to replicate immortally
Change in number but not in appearance
What is replicative immortality?
Normal cell replicates through life cycle and dies. Cancer cells don’t die and keep replicating because the express the telomerase enzyme which prevents the telomere caps from falling off in older cells (telomeres get shorter and thats part of what kills a cell)
What are the 3 components of local tissue invasion?
- Mechanical pressure
- Release of lytic enzymes
- Motility of the cancer cells`
Explain the role of the ECM
The basement membrane (extracellular matrix) is critical in keeping tissue boundaries and cell to cell communication
Chemical signals from the ECM to the cells above let the cells know they are on home ground. If these cells inappropriately detach from the ECM, a cytokine message is sent resulting in apoptosis
Explain mechanical pressure in local invasion?
Pressure builds up in local area (finger like projection), moves along the line of least mechanical resistance, increase in pressure will block capillary blood flow to local tissue
Explain the lytic enzyme involvement in local invasion
Cancer cells secrete lytic enzymes to digest physical barriers to facilitate movement within a tissue or organ
Type IV Collagenase and plasminogen activator are the MOST important
What is Type IV collegenase’s role?
Digests type IV collagen in the ECM in vascular and epithelial basement membranes
What is plasminogen activator’s role?
Convert serum proenzyme plasminogen into protease plasmin which will degrade a variety of proteins
Explain motility in local invasion
Cancer cells produce a cytokine called autocrine motility factor and produce a invadopodia that facilitate movement of cancer cells through basement membrane of tissues by grabbing onto fibronectin (like a fibronectin rock wall)
Explain the dissemination of cancer cells into the lymphatic system and bloodstream
Cells will relocate through lymphatic or circulatory system
Tricks for travelling:
* clump together = harder to phagocytose
* Cover themselves in platelets so they don’t look foreign
Challenge for travelling:
* Turbulent blood flow which is why they clump together to increase chance of survival
* They have to encounter lots of immune cells in their journey
Explain the metastatic establishment step
Local invasion tactics are re-used to leave the lymph or circulatory system (enzymes, motility, pressure)
Vascular endothelial growth occurs
- once tumour is bigger than 2cm it needs its own blood supply
Nutrition
- anorexia-cachexia syndrome: tumour induced starvation
Hormonal support:
- tumour uses body’s own hormones to stimulate growth
Where does breast cancer usually metastasize?
Brain, lungs and bone
Where does colon/bowel cancer metastasize?
Liver, bone
Where does lung cancer usually metastasize?
Brain and bone
Why is grading tumours important and what is it based on?
- Grading and staging sets paramedics of the clinical gravity of the disease
- Grading is based on the degree of differentiation of the cancer in comparison with tissue of origin
Explain differentiation
process of a cell becoming progressively more specialized in function and
structure
Explain poorly differentiated cancer cells
- Mutated early in cell division
- Little resemblance to tissue of origin
- Harder to treat, more unpredictable, more AGG cancer
Explain well differentiated cells
Look like tissue of origin, more predictable treatment wise and in their growth pattern
What does the TNM system stand for?
Primary tumour and it’s extent
Regional lymph node involvement
Metastases
What are tumour markers and what are they used for?
Proteins, enzymes and antigens in blood. Not all cancers have tumour markers.
They are used to screen high risk people for presence of cancer
Used for diagnosis and to identify primary origin of cancer
Monitor effectiveness
Check for recurrence
