Principles of tumours Flashcards
What is neoplasia
A state of AUTONOMOUS cell division - ie. cell proliferation occuring in the absence of any continuing external stimulus (this is what distinguishes neoplasia from hyperplasia). It is a CLONAL PROLIFERATION
(originates from a single cell).
What is a neoplasm
An abnormal mass of tissue which shows uncoordinated growth and shows no useful purpose.
Describe the macroscopic appearance of a benign tumour
- Slow growing
- Well circumscribed
- Often encapsulated by a layer of fibrous tissue
- Not locally invasive
- No metastatic potential
Describe the macroscopic appearance of malignant tumours
- faster growing
- poorly circumscribed
- non-encapsulated
- INVASIVE GROWTH = with destruction of adjacent normal tissue
- METASTATIC POTENTIAL
What is the definition of cancer
A malignant tumour.
There is invasive growth and metastatic potential
Describe the microscopic appearance of benign tumours
- Tumour cells closely resemble cell of origin (well differentiated)
- Cells are uniform throughout the tumour
- Few mitoses
- Tumour cells have a normal nuclear:cytoplasmic ratio
Describe the microscopic appearance of malignant tumours
- May or may not closely resemble the cell of origin - ie. variable differentiation
- cells and nuclei vary in shape and size (pleiomorphism)
- many mitoses
- high nuclear:cytoplasmic ratio
- nuclear staining (hyperchromatism)
What are the defining features of malignancy?
Invasive growth and ability to metastasise
What are the different types of epithelium, and where are they found?
1) squamous epithelium = skin and oesophagus
2) glandular epithelium = respiratory and GIT
3) urothelium = urinary tract
What is a squamous cell papilloma
A benign tumour of the squamous epithelium (skin and oesophagus)
What is a squamous cell carcinoma
A malignant tumour of the squamous epithelium (skin and oesophagus)
What is an adenoma
A benign tumour of the glandular epithelium (respiratory and GIT)
What is an adenocarcinoma
A malignant tumour of the glandular epithelium (respiratory and GIT)
What is a urothelial papilloma
A benign tumour of the urothelium (urinary tract)
What is a urothelial carcinoma
A malignant tumour of the urothelium (urinary tract)
What is a carcinoma
A malignant tumour arising from epithelia
What is the most common type of malignant tumour
Carcinoma
How do carcinomas typically metastasise
Lymphatics
What are the most common types of carcinomas
Adenocarcinoma and squamous cell carcinoma
What are the defining features of adenocarcinomas
- Gland (acinus) formation
- mucin production
What are the defining features of squamous cell carcinomas
- keratin formation
- intercellular bridges between cells
What is a sarcoma
A malignant tumour arising from connective tissue
Where do leiomyomas / leiomyosarcomas arise from?
Smooth muscle
Where do rhabdomyomas / rhabdomyosarcomas arise from?
Skeletal muscle
Where do lipomas / liposarcomas arise from?
Adipose tissue
Where do angiomas / angiosarcomas arise from?
Blood vessels
Where do osteomas / ostesarcomas arise from?
Bone
Where do chondromas / chondrosarcomas arise from?
Cartilage
How do sarcomas metastasise?
Bloodstream
What is grade
GRADE IS THE AGGRESSIVENESS OF BEHAVIOUR OF A CANCER.
Reflects how closely the tumour resembles the normal tissue. Assessment of differentiation.
Tumour grade correlates with aggressiveness of behaviour (how quickly it is growing, and how likely it is to spread)
What does grade 1 cancer mean
Well differentiated - less aggressive behaviour
What does grade 3 cancer mean
Poorly differentiated - more aggressive behaviour
How are carcinomas graded
Usually 1-3, but some exceptions:
- Renal cell carcinoma = Fuhrman
- Prostatic carcinoma = Gleason
- some are not graded eg. small cell lung cancer / BCC
How are lymphomas graded
- Hodgekin lymphoma = not graded clinically
- Non-hodgkin lymphoma = not formally graded; informally classified as low/high grade
What is stage
STAGE IS THE EXTENT OF ANATOMICAL SPREAD BY A CANCER.
Determining how much cancer there is in the body and where it is located.
How is staging performed
- Clinical (physical examination)
- Radiological (CT scans, MRI scans, PET scans, radiographs, USS)
- Surgical - EUA
- Pathological (microscopic examination of tissues)
Why is staging performed
- Usually the single most important prognostic factor
- Helps to plan tx
- Allows doctors to easily communicate
- Clinical trial suitability for patient
What is the most common staging system
TNM
Local tumour spread = how deep they invade the wall of the viscus and whether they invade adjacent structures (colorectum, endometrium, bladder)
Regional lymph node metastasis
The presence of distant metastases
What is the staging system for gynaecological cancers
FIGO
What is the staging system for colorectal cancer
Dukes
What is the staging system for lymphomas
Ann-Arbor
Patient presents to GP with suspected cancer- what should be done
Urgent referral to relavant hospital clinic, usually ‘two week rule’: clinical assessment, investigations (blood tests, imaging, biopsy/FNA)
A patient has been referred to you from GP under 2 week rule. You think cancer is likely- what must be done
A definate diagnosis of cancer requires a ‘tissue’ diagnosis - usually a biopsy for histology. This will also provide the grade.
A patient has just had a biopsy that confirms the diagnosis of cancer. What further investigation is needed?
Staging e.g. CT/MRI
How is a cancer patient managed
All patients are discussed at a cacner MDT meeting and a cancer plan is agreed.
Low stage = curative intent
High stage = palliative intent
List common sites of metastases and their symptoms
Lung = haemoptysis, pneumonia, pleural effusion
Liver = jaundice, hepatic failure
Brain = seizures, stroke
Bone marrow = anaemia, leukopaenia, thrombocytopaenia
bone = pain, fracture, spinal cord compression
What are the categories for types of symptoms a patient may experience
Local symptoms - related to the tissue destruction at the site of the cancer
Metastatic symptoms - related to secondary deposits of the cancer in distant organs
Systemic symptoms - as a result of cytokine release form tumour cells
What systemic symptoms may patients experience
Prolonged fever
Weight loss
Loss of appetite
Decreased immunity
What is a paraneoplastic syndrome
A syndrome caused by substanced produced by the tumour cells which act remotely from the tumour or its metastases
What causes paraneoplastic syndrome
substances released from tumour cells - hormones / cytokines / other factors
OR it can be caused by Abx produced by the body to fight the tumour, but unfortunately cross-react with normal tissues and damage them
List examples of paraneoplastic syndromes
1) Endocrine = hypercalacaemia (PTH secretion) / cushings (ACTH secretion)
2) neuromuscular = eaton-lambert myasthenic syndrome
3) Haematological = PE (release of tumour procoagulants)
4) Renal = nephrotic syndrome (immune complex deposition in glomeruli)
What are the 4 ways cells adapt to their environment
1) atrophy = reduction in the size of an organ
2) hypertrophy = increase in size of cells
3) hyperplasia = increase in number of cells
4) metaplasia = one mature cell type is replaced by another mature cell type
What is metaplasia
one mature cell type is replaced by another mature cell type (change in pattern of differentiation).
It is seen almost exclusively in epithelial cells, usualy as a response to chronic injury.
May progress to dysplasia.
Explain the possible metaplastic change in acidic environment of the vagina
Columnar (glandular) epithelium of the cervix becoming squamous epithelium
Explain the possible metastatic change with cigarette smoking
Columnar (glandular) epithelium of the bronchial tree becoming squamous epithelium
Explain possible metastatic change with gastric acid in the oesophagus
Squamous epithelium of the oesophagus becoming columnar (glandular) epithelium
(BARRETT’S OESOPHAGUS)
What is dysplasia
Disordered growth or differentiation. It may progress to become a malignant tumour (pre-malignant).
How is dysplasia categorised microscopically
By varying degrees of decreased differentiation, more mitoses, high nuclear:cytoplasmic ratio; cellular/nuclear pleomorphism.
Ie. beggining to show the microscopic features associated with malignancy
How is dysplasia categorised
“graded” according to the severity of the changes seen on histology.
mild / moderate / severe
OR
low / high
What is carcinoma in situ
At some anatomical sites, severe dysplasia is called carcinoma in situ.
This is not cancer becuase the cells have not yet invaded through the basement membrane.
What is the basement membrane
A specialised sheet of ECM which lies between parenchymal cells and mesenchymal tissues.
Parenchymal = perform the main function of a tissue, in this context the epithelium.
Support (mesenchymal) cells = provide the structural scaffold of a tissue.
