Cancer

Question 1

What is a tumour?

Answer 1

Any type of mass forming a lesion - does not tell you the cause
May be neoplastic, hamartomatous or inflammatory (e.g. nasal polyps)

Question 2

What is a neoplasm?

Answer 2

The autonomous (happens regardless of what goes on around it) growth of tissue which which have escaped normal constraints on cell proliferation and growth
exceeds that of normal tissues
Normally growth occurs all the time, but is controlled by specific stimuli and feedback loops
In a neoplasm, however, growth is uncoordinated and persists after the cessation of the stimuli that initiated the change

Question 3

What are hamartomas?

Answer 3

Localised benign overgrowths of one of more mature cell types e.g. in the lung
Architectural but not cytological disturbance / abnormalities e.g. lung hamartomas are composed of cartilage and bronchial tissue
So, normal tissue present in the normal part of the body, just organised differently (not a cause for worry)

Question 4

What are heterotopias?

Answer 4

Normal tissue found in parts of the body it normally should not be present e.g. pancreas in the wall of the large intestine

Question 5

What are the 2 types of neoplasm?

Answer 5

Benign - remain localised
Malignant - invades locally and critically, has the potential and often does spread to other, distant sites (more likely to metastasise)

Question 6

What is cancer?

Answer 6

A malignant neoplasm

Question 7

How can you tell the difference between a benign and malignant tumour on an image?

Answer 7

Benign - more clear cut edges, forms away from the tissue

Malignant - infiltrates local tissue, difficult to see when it starts / ends, and where it has spread to

Question 8

Are all benign tumours ‘good’ and all malignant tumours ‘bad’? (use examples)

Answer 8

No
Some malignant tumours do not kill - invade local tissue but do not spread very easily e.g. skin cancers (squamous cell cancers, basal cell cancers)
Some benign tumours kill - almost always due to location, inaccessible for surgical removal e.g. brain tumours

Question 9

How are neoplasms classified? (2 descriptions)

Answer 9

Primarily classified based on the cell origin (on the principle that cancer arises from a normal cell counterpart)
Secondly classified as benign or malignant

Question 10

What are the suffixes to differentiate the naming between a benign and malignant tumour?

Answer 10

Benign: ‘-oma’
Malignant: Either ‘-sarcoma’ or ‘-carcinoma’

Question 11

How to differentiate between a ‘-sarcoma’ and ‘-carcinoma’?

Answer 11

‘-sarcoma’:
Stromal tumours - (soft) tissue around the cancer cells which consists of connective tissue, blood vessels, macrophages, lymphocytes - it’s a supportive system for the cancer cells
More likely to spread via lymphatics
‘-carcinoma’:
Parenchymal tumours - the cancer cells that have been transformed
More likely to spread via blood vessels

Question 12

What are some common exceptions of the naming rules?

Answer 12

Ending in '-oma' but being malignant:
Some teratomas
Hepatoma (liver cell cancer)
Lymphoma
Melanoma
Malignant tumour of the bone marrow - leukemia

Question 13

For example, how would you name a benign or malignant tumour of the cartilage?

Answer 13

‘chondro-‘ = cartilage

Therefore, chondroma (benign) or chondrosarcoma (malignant)

Question 14

What are teratomas?

Answer 14

A rare type of tumour composed of tissues not normally present at the site
Can be anything (benign or malignant)
Derives from germ cell and contain tissues from all 3 germ cell layers (endo, meso and ectoderm)
Can be mature tissues or immature (fetal) tissues
e.g. common in the ovaries - tumours often have hair, teeth and bone

Question 15

What are the 4 main differences between benign and malignant neoplasms?

Answer 15

1. Differences in differentiation - malignant tumours show anaplasia, benign tumour cells are relatively well differentiated
   A well differentiated tumour is one where we can recognise which tissue it came from
2. Rate of Growth - benign tumours are slower growing than malignant tumours
3. Local Invasion - benign tumours don’t tend to infiltrate the basal lamina, malignant tumours infiltrate the basal lamina
4. Metastasis - benign tumours don’t metastasise

Question 16

Define invasion:

Answer 16

Direct extension into the adjacent connective tissue and /or other structures e.g. blood vessels

Question 17

What is dysplasia?

Answer 17

Abnormal cells within a tissue, perhaps a stage preceding to cancer (pre-malignant)

Question 18

What is the major difference between dysplasia and cancer?

Answer 18

There is no invasion in dysplasia, but local invasion of the basement membrane in cancer

Question 19

What is metastasis?

Answer 19

Spread via blood vessels to other parts of the body

All malignant tumours have the capacity to metastasise, although they may be diagnosed before they have done so

Question 20

Which blood vessels are cancers more likely to spread through and why?

Answer 20

Veins because arteries have thick walls with lots of muscle and elastin which makes it more difficult to infiltrate

Question 21

How can cancer spread via body cavities (transcoelomic) and/or direct extention?

Answer 21

By the tumour extending through the pleural cavities/pericardium/peritoneum and maybe even the subarachnoid space, e.g. ovarian tumours commonly metastasise to the liver via the peritoneal cavity
The tumour extends directly through tissue, not via the blood or lymphatics - e.g. from the gallbladder to the liver

Question 22

Define differentiation when referring to neoplasms (and the structures of malignant tumour differentiated cells):

Answer 22

How much the cells of the tumour resemble the cells of the tissue it is derived from
Tumour cells tend to have larger nuclei (and hence a higher nuclear-cytoplasmic ratio) and more mitoses than the normal tissue they are derived from.
They may have abnormal mitoses (e.g. tripolar) and marked nuclear pleomorphism (variability in nuclear size and shape)

Question 23

What is meant by growth pattern?

Answer 23

The architecture of the tumour compared to the architecture of the tissue it is derived from
Tumours have less well defined architecture than the tissue they are derived from
Generally, the more abnormalities in the structure, the more malignant the tumour

Question 24

What is the process of benign tumours becoming malignant?

Answer 24

Hyperproliferation, causing small bump (but more or less normal)
Increase in cells leads to dysplasia e.g. polyps
Severe dysplasia - more nuclear abnormalities (precancerous as it has not yet invaded the basement membrane)
Cancer - abnormal cell growth invades basement membrane
Invasive cancer / metastasis - invades blood vessels

Question 25

What are the 5 routes tumours can use to spread?

Answer 25

1. Direct extension
2. Haematogenous
3. Lymphatic
4. Transcoelomic
5. Perineural

Question 26

What is the mechanism of direct extension for the spread of tumours?

Answer 26

Direct invasion in continuity 
Includes fibroblastic (stroma) proliferation (a desmoplastic response) and vascular proliferation (angiogenesis)
e.g. basal cell cancer spread through the bone, through the meninges, into the brain
or e.g. gall bladder cancer directly extending into the liver

Question 27

What do tumours require to grow?

Answer 27

Stromal support (i.e. blood vessels)

Question 28

What is the mechanism of haematogenous spread of tumours?

Answer 28

Via blood vessels
Generally via the venules / capillaries as they have thinner walls compared to arterioles / arteries
Sarcomas tend to metastasise via this route (although some carcinomas do too)

Question 29

What is the mechanism of the lymphatics for spread of tumours?

Answer 29

Via the lymphatic system to the lymph nodes, which go into the thoracic duct and into the the superior vena cava
From there, can travel to any other part of the body
Easy to invade as there are no tight junctions between the cells in the lymphatic system
Pattern of spread can be traced by following the normal lymphatic drainage pattern from primary tumour site
Most epithelial cancers / carcinomas metastasise via the lymphatics first

Question 30

What is the transcoelomic mechanism for spread of tumours?

Answer 30

Via the body cavities
Most common examples are the pleural cavities (for intrathoracic cancers) and the peritoneal cavities (for intra-abdominal cancers)
Tends to be moist and moving e.g. gastric cancers, reaches and penetrates the peritoneum - moist and lack of resistance allows for smooth movement of the cancer

Question 31

What is the pleural cavity?

Answer 31

Thin fluid-filled space between the two pulmonary pleurae (pair of serous membranes lining the thorax and enveloping the lungs) of each lung

Question 32

What is the peritoneal cavity?

Answer 32

Fluid-filled space between the peritoneums that outline the abdomen and organs

Question 33

What is the perineural mechanism for spread of tumours?

Answer 33

Via nerves
e.g. pancreatic cancer spread via the nerves to the celiac trunk (first major branch of the abdominal aorta), and eventually to the liver

Question 34

How is tumour spread assessed?

Answer 34

Triad / Triple assessment:
1. Clinically
2. Radiologically
3. Pathologically 

Question 35

How to clinically assess tumour spread?

Answer 35

Examining the patient - whether the lump is fixed or not fixed e.g. if a breast lump can be moved around, and is unattached to the skin/muscle underneath, more likely to be benign, whereas, if it fixed to the underlying muscle, more likely to be malignant
Examine lymph nodes to see if it has spread, etc.

Question 36

How to radiologically assess tumour spread?

Answer 36

Imaging

Question 37

How to pathologically assess tumour spread?

Answer 37

Biopsy the tumour / lymph node
Frozen section (pathological lab procedure, perform rapid microscopic analysis of a specimen)

Question 38

How to describe tumour spread (stage)?

Answer 38

TNM staging system: Each individual organ / type of cancer has it’s own system, this is a book that is the reference system describing cancer and its spread
T = tumour, size and how far the tumour has spread (i.e. extent of local invasion)
N = Nodes, number of lymph nodes involved / affected
M = Metastases, presence and number of distant metastases

Question 39

What 2 ways can cancers be described using?

Answer 39

Grade and stage

Question 40

What is grade Vs what is stage?

Answer 40

Grade - how differentiated is the tumour? i.e. how bad does the primary look down the microscope - irregularites in the cytology / architecture
Stage - how far has the tumour spread (using the TNM system)

Question 41

Which is better to use / take into consideration for prognosis?

Answer 41

Stage - determines prognosis

Although tumours high in grade tend to also be high in stage

Question 42

Grid for epithelial neoplasms:

Answer 42

Benign, Malignant, Examples:
Squamous - squamous epithelioma / papilloma, squamous cell carcinoma, skin / oesophagus / cervix
Glandular - adenoma, adenocarcinoma, breast / colon / thyroid / pancreas
Transitional - transitional papilloma, transitional cell carcinoma, bladder

Question 43

Grid for connective tissue neoplasms:

Answer 43

Benign, Malignant, Examples:
Smooth muscle - leiomyoma, leiomyosarcoma, uterus / colon
Bone - osteoma, osteosarcoma, arm / leg