More disorders of tissue growth Flashcards
How do benign and malignant tumours compare in terms of growth rate?
Benign - slow
Malignant - fast
How do benign and malignant tumours compare in terms of demarcation (growth limits)
Benign tumours may reach limit
Malignant have no limit
How do benign and malignant tumours compare in terms of invasion?
Benign - no invasion
Malignant - invasion
How do benign and malignant tumours compare in terms of resemblance to original architecture?
Benign resemble original tissue
Malignant may or may not resemble original tissue
How do benign and malignant tumours compare in terms of anaplasia?
Benign have no anaplasia
Malignant may or may not have anaplasia
Give 5 examples of how malignant and benign tumours differ
Benign - localised, expansile growth, stroma produced by neighbouring cells, growth limit, resemble original tissue, no metastasis
Malignant - infiltrative growth, produce own stroma, may not resemble original tissue, metastasise, no growth limit
What are tumour associated macrophages?
Macrophages present in tumours
M1 = tumoricidal (better prognosis)
M2 = relevant role
What is an oncogene?
A gene that drives neoplastic transformation
drive tumour development
What is a proto-oncogene?
Normal cellular gene that regulates the cell cycle
What is a viral-oncogene?
Oncogene in virus DNA/RNA
Infection with virus causes it to become an oncogene
What are carcinogenic agents? What type of agents are they?
Agents that cause malignant neoplasia in cells
Chemicals, irradiation, infectious agents
Carniogenic agents can be direct or indirect. What do these terms mean?
Direct - need no chemical transformation (ultimate carcinogens)
Indirect - need chemical transformation, usually metabolised in the liver (pro-carcinogens)
Both indirect and direct carcinogenic agents are highy reactive what? What do they do?
Electrophiles
Bind to DNA/RNA/protiens to form covalent bond
Chemical carcinogenesis requires 2 steps. What are these?
Initiation - irreversible genetic change
Promotion - damaged DNA replicates so change becomes fixed
What are promoters? What do they do?
Regions of DNA that initiate transcription of a gene
Stimulate division of mutated cells
Give examples of promoters
Carcinogens Radiation Viruses Hormones Parasites Dietary factors
Give an example of a direct carcinogen and an indirect carcinogen
Direct - anticancer drug
Indirect - tobacco
How do different doses of radiation damage cells?
Low dose - DNA damage
Mild dose - repair or tumor
High dose - apoptosis
Radiation can be ionising or non-ionising. What do these terms mean? Give an example of each
Ionising - not enough energy to displace electrons from atoms e.g. UV
Non-ionising - enough energy to displace electrons from atoms e.g. X-rays
Give an example of a hormone that increase risk of tumours.
Oestrogen - increased risk of mammary tumours
Mutated cells can lead to increased function of loss or function. What type of genes cause each of these?
Non-functioning - by tumour or suppressor gene
Functioning - by growth promoting or normal gene
When are cells checked for damage or unduplicated DNA?
Only if proliferating
Tumours have a limitless reactive potential. What is this?
Normal cells stop replicating after certain time length due to shortening of telomeres at end of chromosome
Tumour and stem cells have telomerase - maintain normal telomere length and allow continued replication
Which individuals are more susceptible to tumours?
Immunocompromised
What cells are tumour specific antigens found on?
Antigens found on restricted tumour cells
What cells are tumour associated antigens found on?
Antigens found on both normal and tumour cells
Tumour = overexpressed
What can be used as a non-invasive way of diagnosing cancer, when they have been released into the bloodstream?
Tumour specific antigens
Tumour associated antigens
Why are tumour associated antigens not good targets for therapeutic purposes?
On both normal and tumour cells
What are the 4 ways tumour evade the immune system response?
Reduce expression of MHC
Antigen masking - hide tumour associated/specific antigens
Immunosuppression
Tolerance
What are the direct effects of malignant or benign tumours?
Obstruction Pressure Replacement of normal tissue (malignant) Dyshaematopoiesis Bone fracture Malabsorption Haemorrhage Infection
Tumours can cause mural or extra mural obstruction. What do these mean? What does obstruction use?
Mural - against cavity wall
Extra mural - outside cavity wall
Disruption of arterial, venous and lymphatic flow
Tumours can induce pressure on surrounding tissue. What might this cause the tissue to do if in a non-expandable cavity?
Atrophy
How can tumours cause dyshaematopoiesis?
Invade myeloid tissue
What are secondary tumours?
Tumours caused by metastasis from the original tumour location (primary tumour)
How can tumours cause malabsorption?
If in gut wall, cause thickening which reduces absorption
Tumours can cause haemorrhages. They can be chronic or acute. What are the results of these?
Acute - possibly fatal, hypovolaemic shock
Chronic - anaemia
Why are secondary infections common with tumours?
Epithelial ulceration
Immunosuppression
What are some indirect effects of tumours?
Paraneoplastic syndromes
Hormonal effects
Hypertrophic pulmonary oesteoarthropathy
What is paraneoplastic syndrome?
Systemic complications caused by tumour cell products, not the tumour itself
Do benign or malignant tumours alter hormones more as part of their indirect effect?
Benign - keep cell architecture (requires some differentiation)
What is tumour cachexia (wasting syndrome)?
Loss of fat and muscle due to tumour
Causes anorexia or polyphagia
How can tumour cells cause polyphagia/anorexia in tumour cachexia? (Wasting syndrome)
Tumour cells produce cytokines
Act on brain to cause change in appetite
