Neoplasia Flashcards
What is oncology?
Branch of medicine which studies malignant tumours and treatment
What is a neoplasm?
- new growth (tumour)
- genetic disorder of cell growth triggered by acquired or less commonly inherited mutations (single cell)
- abnormal mass of tissue
- uncoordinated growth which exceeds that of normal tissues
- growth persist after stimuli is removed
What are the two categories within the classification of tumours?
- clinical behaviour
- histogenesis (tissue of origin)
What are classifications of tumours within clinical behaviour?
- benign
- malignant
What are classifications of tumours within histogenesis?
- epithelial
- connective tissue
- other tissue
Growth pattern benign vs malignant?
- benign grow by method of localised expansion due to them being encapsulated (easier to remove)
- malignant grow by metastasis (they can travel to other organs/sites in the body to form a new tumour) invasion/infiltration as they have no surrounding capsule
Growth rate benign vs malignant?
- benign tumour growth tends to be slow
- malignant tumour can grow rapidly, but this is variable
Histology benign vs malignant?
- benign tumour cells resemble the tissue of origin (differentiation), they are the same size and shape and there may be a few mitotic cells (within normal limit)
- malignant cells have variable resemblance to their tissue of origin, cellular and nuclear pleomorphism (different size/shapes), many mitotic cells (abnormal amount)
Clinical effects benign vs malignant?
- a benign tumour can cause a lump or pressure or obstruction in the area depending on the site and size, if the arise from endocrine gland there can be an increase/decrease in hormone production, treated by local excision (surgery)
- a malignant tumour can cause pressure or infiltration or destruction to the area, if endocrine can also affect hormone secretion, treated by local excision and chemotherapy or radiation (if metastases present)
What are the effects of benign tumours?
- varies depending on size, site and tumour
- palpable lump
- pressure
- obstruction
- function eg hormone secretion
- the effect may not always be benign
What is an examples of a benign tumour in the head and neck?
- benign tumour affecting salivary gland - pleomorphic adenoma (potential to cause pressure on facial nerve)
What is an example of a malignant tumour in the head and neck?
- squamous cell carcinoma of tongue and larynx
What are the two components which compose all tumours?
- neoplastic cells
- reactive stroma
What do neoplastic cells constitute?
The tumour parenchyma
What is the reactive stoma made up of?
Connective tissue, blood vessels and cells of adaptive/innate immune cells
What is a malignant epithelium called?
Carcinoma
What is a benign squamous epithelium?
Papilloma
What shows a malignant connective tissue?
Sarcoma
What is a benign glandular epithelium?
Adenoma
What is a malignant squamous epithelium?
Squamous cell carcinoma
What is a malignant glandular epithelium?
Adenocarcinoma
what do potentially malignant disorders of the oral cavity indicate?
Risk of likely future malignancies occurring in the oral mucosa
What is a leukoplakia?
Which patch that cannot be rubbed off or attributed to any other cause
How is the potential of a malignancy assessed?
By taking a biopsy and assessing for dysplasia
What does a tissue which shows dysplasia indicate?
Potential to become malignant
What is dysplasia?
Abnormality (changes in shape/size) confined to epithelium
What are potential aetiology for oral cancer?
- tobacco
- betel quid
- alcohol
- diet/nutrition
- oral hygiene
- viruses eg HPV
- immunodeficiency
- socioeconomic factors (deprived area)
- GORD
What are the two groups of factors within carcinogenesis?
Environmental (carcinogens)
And
Genetic
What are carcinogens for benign tumours?
- inherited
- viruses
What are carcinogens for malignant tumours?
- chemical agents
- physical agents
- viruses
- may affect tissue directly or indirectly
What is the multi-step theory of carcinogenesis?
- initiation
- promotion
- progression
- latency period
Describe the initiation step of carcinogenesis
Carcinogen induces a genetic change resulting in a neoplastic potential
Describe the promotion stage of carcinogenesis
Another factor stimulates the initiated cell for division (clinal proliferation)
Describe the progression step in carcinogenesis
Additional mutations resulting in malignancy
What are examples of chemical carcinogens?
- smoking polycyclic hydrocarbons (includes tars)
- diet
- drugs
- alcohol
- asbestos
What are examples of physical carcinogenesis?
- ionising radiation (damages DNA causing mutations)
- radioactive metals and gases (radium bone and bone marrow tumours)
- UV light damages skin leading to skin cancer (sun beds)
Which type of tissues are most sensitive to radiation?
Embryonic tissues
What are examples of viral carcinogenesis?
- DNA viruses
- RNA viruses
What are the genes which accelerate cancer?
Oncogenes
What are the genes which prevent cancer?
Tumour suppressor genes
What are protooncogenes?
Normal genes which regulate cell division
What do oncogenes produce?
Oncoproteins
How do genes become deregulated?
Tight regulation is lost
- mutation (increased activity of product)
- excess normal product (duplication of gene/viral product)
- enhanced transcription (translocation/chromosome rearrangement)
How do tumour suppressor genes act?
- act to inhibit cell division and suppress growth
- act as anti oncogenes
- require loss of both alleles
- retinoblastoma gene
TP53
- acts just before the restriction point in the cell cycle
- stops the cell cycle to allow for DNA repair
- initiates apoptosis if repair isn’t possible
- often inactivated in cancer (common in HPV)
What are examples of genetic susceptibility to cancer?
- inherited cancer syndromes (single mutant genes, eg retinoblastoma)
- familial cancer (family clusters, genes and inheritance patterns unclear, eg breast cancer)
- defective DNA repair (increased sensitivity to carcinogens and general increased cancer risk eg xeroderma pigmetosum)
How may a cancer cell differ
What are modes of spread of malignant tumours?
- local spread
- lymphatic spread
- blood spread (haematogenous)
- transcoelomic spread
- intraepithelial spread
What is metastasis?
Spread of the malignant cells to distant organs forming secondary tumours
What is the pattern of spread of carcinomas?
- lymphatics first
- then blood later
What is the pattern of spread of sarcomas?
Blood spread (rarely lymphatic
What is used for tumour grading?
Microscope
What is used for tumour staging?
Clinical tests
Describe grading of tumours
Histological assessment of:
- invasion into underlying tissue
- cellular atypia
- many methods eg numerical grades/low-high/degree of differentiation
What does cancer staging describe?
The extent or severity of a persons cancer
- helps treatment planning
- helps estimate the persons prognosis
Methods include:
- physical exams
- imaging procedures
- lab tests
Etc.
What clinical staging system is used for oral cancer?
TNM (tumour size, lymph node involvement, presence of metastases)
How does the immune system recognise tumour cells?
- tumour associate dantigens TAAs
- neoantigens
- products of mutated genes
- overexpressed proteins
- viral proteins eg HPV
What is the tumour response to tumour antigens?
A cell mediated immune response
- CD8+
- NKC
- macrophages
How do tumour cells escape immune response?
- alter tumour antigen expression
- activation of immunoregulatory pathways leading to T cell unresponsiveness and apoptosis
- immunosuppressive factors eg cytokines which inhibit T cell response
What is immunotherapy?
Uses the patients own immune response to control and destroy malignant cells
- active immunisation
- reversal of immunosuppression
- adopted cell transfer
- strengthening natural immune responses
