Cancer Flashcards
Define a tumour
Any kind of mass forming lesion.
May be neoplastic, hamartomatous or inflammatory (e.g. nasal polyps inflammatory lumps in nose).
Define neoplasm
The autonomous growth of tissue which have escaped constraints on cell proliferation
Dysregulated growth
What are the two broad descriptions that we have to describe neoplasms?
Benign - remain localised
Malignant - invade locally/spread to distant sites - this spread is called metastasis
What kind of tumour is a cancer?
Malignant neoplasms
What are the differences in appearance between benign and malignant neoplasms?
benign neoplasm- well contained, smooth round appearance
malignant neoplasm- not well demarcated margins, hard to describe where it starts and ends
What are the 6 hallmark features of neoplastic cells (cancerous)?
Evading apoptosis Sustained angiogenesis limitless replicative potential Insensitivity to anti-growth signals Tissue invasion and metastasis Self-sufficiency in growth signals
Define what is meant by a hamartoma
Tissue is found in the wrong place in an organ
Localised benign overgrowths of one or more mature cells types
ie overgrowth of cartilage tissue in lungs
represent architectural not cytological abnormalities
Why are hamartomas more common in children?
usually caused by genetic abnormalities in important developmental genes.
Define what is meant by heterotopia
Normal tissue being found in parts of the body where they are not usually present
ie pancreas tissue on intestinal wall
Define what is meant by a teratoma
These are tumours derived from germ cells and can contain tissue derive from all three for 3 germ cell layers
They may contain mature and / or immature tissue and even cancers.
(The 3 germ layers are ectoderm, endoderm and mesoderm)
What are the usual stems and suffixes used to describe neoplasms?
Stem = relevant tissue
Suffix
= oma if benign
= sarcoma if malignant
What are exceptions to the normal rules for naming cancers?
All malignant neoplasms Hepatoma - liver Melanoma - melanocytes Mesothelioma - pleural tissue Seminoma - germ cell neoplasm of testis Lymphoma - lymphocytes
What is meant by invasion?
This means direct extension into the adjacent connective tissue and /or other structures e.g. blood vessels.
This is what distinguishes dysplasia/carcinoma in situ from cancer.
Describe how invasion can be used to distinguish between benign and malignant neoplasms
Malignant tumours infiltrate and destroy the surrounding tissue, poorly demarcated
Invasion will often trigger an immune response- so we will see lymphocytes on histology
Most benign tumours grow as cohesive, expansile masses that remain localised to their site of origin (encapsulated)- don’t infiltrate surrounding tissue
Describe how invasion can be used to distinguish between benign and malignant neoplasms
Malignant tumours infiltrate and destroy the surrounding tissue, poorly demarcated
Invasion will often trigger an immune response- so we will see lymphocytes on histology
Most benign tumours grow as cohesive, expansile masses that remain localised to their site of origin (encapsulated)- don’t infiltrate surrounding tissue
Describe what is meant by metastasis
This means spread ,via blood vessels etc, to other parts of the body.
All malignant tumours have the capacity to metastasise
Formation of discontinuous tumour implants at a distance from the main tumour mass
Only gliomas and basal cell carcinomas cannot metastasise
Where does a carcinoma cancer begin?
cancer that begins in the skin or in tissues that line or cover internal organs
Where does a sarcoma cancer begin?
cancer that begins in bone, cartilage, fat, muscle, blood vessels, or other connective or supportive tissue.
Describe how metastasis can be used to distinguish between benign and malignant neoplasms
Benign neoplasms: Cannot metastasise
Malignant neoplasms: Can metastasise
Describe what is meant by differentiation in cancer?
This means how much do the parenchymal cells of the tumour resemble the cells of the tissue it is derived from.
Parenchyma= functional cells
Well differentiated= looks like normal tissue
Poorly differentiated= looks nothing like normal tissue
Describe how neoplastic cells can look different from normal cells
Large, variably shaped nuclei
Many dividing cells (disorganised)
Variation in size and shape
Loss of normal features
Describe how differentiation can be used to distinguish between benign and malignant neoplasms
Benign: Often well differentiated
Malignant: Can show various levels of differentiation
Anaplastic= no differentiation at all (no specialized or functional features of cells seen)
What are anaplastic cells?
A term used to describe cancer cells that divide rapidly and have little or no resemblance to normal cells.
Describe what is meant by the growth pattern of the tumour
This means how much does the architecture of the tumour resembles the architecture of the tissue it is derived from.
Tumours have less well defined architecture than the tissue they are derived from.
Describe how growth pattern can be used to distinguish between benign and malignant neoplasms
Benign neoplasms: Grow slowly and so retain normal tissue architecture more
Malignant neoplasms: Grow rapidly and so lose normal tissue architecture.
How does growth rate of a tumour affect differentiation?
Rate of growth correlates with the level of differentiation(faster they grow- the more they lose the normal architecture)
What are the four ways to differentiate benign and malignant tumours?
Invasion
Metastasis
Degree of differentiation
Growth pattern
What are the four ways to differentiate benign and malignant tumours?
Invasion
Metastasis
Degree of differentiation
Growth pattern
What are the 5 ways tumours can spread?
Direct extension Haematogenous Lymphatic Transcoelomic Perineural
Describe how tumours can spread by direct extension
This is associated with a stromal (stromal cells around tissue that support the tumour) response to the tumour.
This includes fibroblastic proliferation (“ a desmoplastic response”), vascular proliferation (angiogenesis) and an immune response.
Describe haematogenous spread of tumours
This is via blood vessels.
The blood vessels usually invaded are the venules and capillaries because they have thinner walls.
Most sarcomas metastasise first via the blood vessels.
Describe lymphatic spread of tumours
This is via lymphatics to lymph nodes and beyond.The pattern of spread is dictated by the normal lymphatic drainage of the organ in question.Most epithelial cancers metastasise first via the lymphatics.
Describe the transcolemic spread of tumours
the spread of a malignancy into body cavities across the peritoneal cavity
This is via seeding of body cavities.
The commonest examples are the pleural cavities (for intrathoracic cancers) and the peritoneal cavities (for intra-abdominal cancers)
Direct seeding of body cavities and surfaces (peritoneal, pleural, pericardial, subarachnoid, joint)-
Describe perineural spread of tumours
This is via nerves
This is an underappreciated route of cancer spread
Nerves have a space around them which tumours use
Describe the 3 ways in which we can assess tumour spread
Clinically - how the patient is doing
Radiologically - imaging of the tumour
Pathologically - sampling of the tumour
Describe how we grade a tumour
Based on degree of differentiation and on the number of mitoses
Name some grading systems for different cancers
Dukes’ – Colorectal
FIGO – Ovarian
Ann Arbor – Lymphoma
Gleason – Prostate
How do benign neoplasms become malignant neoplasms?
Will acquire more and more genetic mutations that enable it to invade the surrounding tissue and spread to other sites
Difficult to find the ‘driver’ mutation that was responsible for the cancerous change
What type of cancer is haematogenous common in?
Liver and lungs are most common site due to venous drainage
Renal cell carcinoma can grow within renal vein to Inferior Vena Cava and into the right atrium.
What causes nodal hyperplasia?
Nodes may contain the spread locally
Evoke an immune response which causes nodal hyperplasia
Not every enlarged node in the region of a tumour contains metastatic spread
How do we describe tumour spread using the TNM system?
This is known as staging:
T = Tumour: the tumour size or extent of local invasion( T1-T4)
N = Nodes: number of lymph nodes involved (1,2,3)
M = Metastases: presence of distant metastases (No,1,2)
This is called the “TNM” system and the details are different for each kind of cancer
What is an example of a benign and malignant tumour of squamous epithelium?
Benign = squamous papilloma Malignant = squamous cell carcinoma
What is an example of a benign and malignant tumour of glandular epithelium?
Benign = adenoma Malignant = adenocarcinoma
What is an example of a benign and malignant tumour of transitional epithelium?
Benign = transitional papilloma Malignant = transitional cell carcinoma
