Tumour classification, tumour grading & staging Flashcards
What is dysplasia?
Disordered cell growth which is a precursor to carcinoma
NOTE: a carcinoma is a malignant tumour of the epithelium.
Also called intraepithelial neoplasia (in the cervix).
Can be caused by longstanding hyperplasia or from metaplasia
potentially reversible if the stressor is removed.
- If the stressor persists, dysplasia can progress to carcinoma, which is irreversible.
Features of dysplasia:
- larger nuclei
- cells are disordered
NOTE: view microscopic image of dysplasia on notes
Compare benign & malignant tumours
Benign tumours:
- remain localised
- slow growing
- Well differentiated malignant tumours closely resemble the tissue from which they arise.
- often circumscribed & encapsulated
Malignant tumours:
- invade surrounding tissues & many have the capacity to metastasise
- Poorly differentiated malignant tumours do not look anything like their tissue of origin.
- usually have irregular margin
Anomaly- basal cell carcinoma- malignant skin tumour which does not metastasise
What are the cytological differences between benign and malignant cells?
Benign cells:
- Low nuclear to cytoplasmic ratio
- all nuclei of similar size
- no hyper chromatic nuclei
- vesicular, evenly distributed chromatin
- smooth nuclear membranes
Malignant cells:
- High nuclear to cytoplasmic ratio i.e. big nuclei.
- Nuclear pleomorphism i.e. variation in size & shape of nucleus.
- Hyperchromasia of nucleus (darker than normal due to extra chromatin)
- Irregular chromatin distribution w/in nucleus (+/- prominent nucleolus)
- Irregular nuclear membranes
How are tumours classified?
Histogenetic classification
- System is based on cell of origin of tumour.
The major categories are:
1. Epithelial cells
2. Connective tissue (mesenchymal cells)
3. Lymphocytes
4. Haematopoietic cells
Examples of histogenetic classification
- Carcinoma:
- A malignant tumour derived from epithelial cells
- Shows jagged irregular ‘islands’ of squamous cell carcinoma under microscope
- Also see keratin production or desmosomes linking the tumour cells. - Adenocarcinoma
- a malignant tumour derived from glands or showing gland formation.
- lumens of the malignant glands shown under microscope
- Also contain Mucin in their cytoplasm. - Adenoma
- benign tumour that shows gland formation. - Sarcoma
- A malignant tumour of connective tissue / mesenchymal tissue.
- Include: mucles, nuerves, tendons, blood vessels, bone, cartilage, adipose & fibrous tissues.
- The suffix -sarcoma = malignant tumour of connective tissue e.g. liposarcoma.
- The suffix -oma = benign tumour e.g. lipoma - Lymphoma or leukaemia
- A malignant tumour of lymphocytes.
- Lymphoma- when it involves lymph nodes causing them to enlarge.
- thin capsule, Subcapsular & medullary sinuses present under microscope in normal lymph nodes. However in lymphoma, can no longer see sinuses & lymph node has many pale nodules (follicular lymphoma).
- Leukemia= If the malignant lymphocytes are present in the bone marrow or in the peripheral blood
- normal blood film= plenty of red blood cells & occasional neutrophils. Leukemia- small atypical lymphocytes (chronic lymphocytic leukaemia). - Leukaemia
- A malignant tumour of haematopoietic cells.
- These are cells involved in haematopoiesis.
What is tumour grade?
The extent to which tumour histologically resembles the cell or tissue of origin.
The higher the tumour grade, the more aggressive the tumour is likely to be in terms of behaviour & the more rapidly it will grow & spread.
Grade 1 = well differentiated, cancer cells look similar to normal cells & grows slowly
- Grade 2 = moderate, cancer cells look different & grow faster than normal cells
- Grade 3 = poorly differentiated, cancer cells look abnormal & grow much more quickly
What is tumour stage?
How large the tumour is.
Extent of tumour spread
Staging:
1- cancer small & hasn’t spread
2- cancer slightly larger + hasn’t spread
3- cancer larger + started to spread to tissue+ cancer cell lymph nodes
4- cancer has spread to another organ
What is TNM system of tumor staging?
T = size of the tumour or extent of local invasion, usually a number between 1 & 4, 1 is a smaller cancer 4 is a larger more advanced cancer
N = whether the cancer has spread to lymph nodes, usually between 0 & 3, 0 means there are no cancer cells in the lymph nodes 3 means there are lots of lymph nodes affected
- Cancer cells in nodes is a sign that the cancer has started to spread.
M = metastases (whether the cancer has spread to another part of the body), usually between 0 & 1, 0 means cancer has not spread to other parts of the body 1 means it has spread
The higher the stage, the worse the prognosis for the patient.
NOTE: view notes for diagram of TNM
E.g.
- a small cancer that has spread to lymph nodes but not to anywhere else in the body may be T2 N1 M0.
What is the importance of grading and staging tumours?
It helps you know which treatments you need
E.g. A local treatment e.g. surgery or radiotherapy if cancer is in 1 place
- could be enough to get rid of the cancer completely.
- A local treatment treats only an area of the body.
If cancer has spread:
- need treatment that circulates throughout the whole body - called systemic treatments
- E.g. chemotherapy, immunotherapy, hormone therapy
What is the purpose of having classification systems e.g. TNM for cancer?
The systems mean that:
- doctors have a common language to describe the size and spread of cancers
- doctors can compare treatment results between research studies
- different hospitals and clinics have standard treatment guidelines
What is the purpose of having classification systems e.g. TNM for cancer?
The systems mean that:
- doctors have a common language to describe the size and spread of cancers
- doctors can compare treatment results between research studies
- different hospitals and clinics have standard treatment guidelines
