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Year 1 Medicine > Tumours > Flashcards

Tumours Flashcards

1
Q

Define a tumour?

A

A tumour is an abnormal growing mass of tissue.

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2
Q

What is the difference between this growth of a tumour and the growth of normal tissue?

A

Tumour growth continues even after the stimulus is removed. It is uncoordinated.

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3
Q

Name the two types of tumour?

A

Benign

Malignant (cancer)

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4
Q

What is a cancer?

A

malignant tumour that can invade into adjacent tissue and metastasise and grow at other sites within the body.

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5
Q

Give some general features of cancer?

A

Major causation of death in UK
Incidents of cancer are increasing
Genetic and environmental factors contribute to causation.
It is a multi-step process of development that is progressive.

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6
Q

What factors affect the classification of tumours?

A

The tissue that they originate from

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7
Q

Where do germ cell tumours originate and what are they referred to?

A

Known as teratomas.
Tumours composed of various tissues.
Develop in ovaries and testis

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8
Q

Give some features of benign tumours?

A 
Non- invasive growth pattern
Encapsulated
No evidence of invasion or metastases. 
Cells similar to normal cells.
Rarely cause death
Function not normally affected.
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9
Q

Give some features of malignant tumours?

A 
Invasive growth pattern
No capsule or capsule breached by tumour cells
Loss of normal function
Abnormal cells
Cancers are poorly differentiated
Often metastases 
Frequently causes death.
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10
Q

Give some properties of cancer cells?

A 
Loss of tumour suppressor genes
Gained function of oncogenes 
Altered cellular function 
Abnormal morphology (size/shape)
Capable of independent growth
No singe one feature unique to all cancer cells
Mitoses present and often abnormal.
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11
Q

What causes spreading of cancers?

A

The loss of cell to cell adhesion and cell to matrix adhesion leads to spreading and cancerous cells can easily break off and deposit elsewhere in the body.

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12
Q

What are tumour biomarkers?

A

Proteins produced by cancer cells that are related to tumour production. E.g Growth factor receptors, oncogenes, immune checkpoint inhibitors.

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13
Q

In what way can tumour biomarkers be useful?

A

Used in screening and early diagnosis of patients. Abnormal levels of these proteins can indicate a patient has a tumour before symptoms would be visible. e.g oestrogen receptor is tested in females for breast cancer.

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14
Q

What is tumour angiogenesis?

A

New blood vessel formation by tumours

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15
Q

What is the function of tumour angiogenesis?

A

Required to sustain tumour growth and provides a rout of release for tumour cells into the circulation.

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16
Q

What regulates tumour cell growth?

A

Apoptosis

Can have a negative effect if healthy cells are programmed to be killed.

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17
Q

Describe secondary invasion of cancer and metastasis?

A

It is a multi-step process and can take different routes - via lymphatics, blood, nearby tissues. It involves the increased degradation of the matrix by proteolytic enzymes and altered adhesion.

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18
Q

What is Trans-coelomic spread?

A

Special form of local spread.

Metastases across a body cavity e.g pleural or peritoneal

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19
Q

Name some common sites for metastasis?

A 
Liver
Lung
Brain
Bone (axial)
Adrenal gland
Omentum
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20
Q

What are some uncommon sites of metastasis?

A

Heart
Spleen
Kidney
Skeletal muscle.

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21
Q

What tissues would these tumours commonly metastasise

  1. Breast
  2. Prostate
  3. Colorectal
  4. Ovary
A
  1. Bone
  2. Bone
  3. Liver
  4. Omentum
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22
Q

What are the local effects of benign tumours?

A

Pressure and Obstruction.

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23
Q

What are the local effects of malignant tumours?

A 
Pressure
Obstruction
Tissue destruction - ulceration and infection
Bleeding - haemorrhage and anaemia
Pain
Effects of treatment.
24
Q

What are the systemic effects of malignant tumours?

A

Weight loss (cancer cachexia)
Secretion of hormones - Normal/Abnormal
Paraneoplastic syndromes

25
Q

Describe normal production of hormones by tumours?

A

Produced by tumours of the endocrine system but there is still abnormal control of its secretion and production.

26
Q

Describe abnormal production of hormones by tumours?

A

Produced by a tumour from an organ that does not normally produce hormones. e.g certain lung cancers can produce ADH.

27
Q

What are paraneoplastic syndromes?

A

Cannot be explained by local or metastatic effects of tumours. They have misleading symptoms and are therefore difficult to recognise and diagnose.

28
Q

When is it best to detect cancer?

A

Early detection, at dysplasia (pre-invasive stage)

29
Q

What is dysplasia?

A

A pre-malignant change that is the earliest possible change in the process of malignancy that can be visualised. There is no invasion but it can progress to cancer.

30
Q

What are some features of dysplasia?

A

Disorganisation of cells - increased nuclear size, mitotic activity and abnormal mitoses.
Grading of dysplasia - high or low throughout normal tissue
No invasion.

31
Q

How is dysplasia currently used in the detection of cancer?

A

Used in cervical screening. Dysplastic cells are detected in the squamous epithelium of the cervix.

32
Q

What is an adenoma?

A

A benign tumour of glandular epithelium

33
Q

What is an Adenocarcinoma?

A

Malignant tumour of glandular epithelium

34
Q

Which biomarker would you monitor for the recurrence of an adenocarcinoma of the colon?

A

Carcinoembryonic antigen

35
Q

How is genetic fidelity ensured in daughter cells?

A

Quality control checkpoints - each cell must receive a full chromosome complement.
Mutations in DNA sequences must not pass on.

36
Q

What are some external factors to cell cycle control?

A

Hormones
Growth factors
Cytokines
Stromas

37
Q

What is the quiescence phase?

A

G0- Resting phase: cell has left the cycle and stopped dividing. (quiet phase).

38
Q

What factors cause G1 and G2 cycle arrest?

A

If cell size inadequate

If DNA damage is detected

39
Q

What factors cause only G1 arrest?

A

If nutrient supply inadequate

Essential external stimulus lacking

40
Q

What factor causes S phase arrest?

A

If the DNA is not replicated

41
Q

What factor causes M phase arrest?

A

Chromosome mis-alignment

42
Q

What are the checkpoints?

A

System of cyclically active and inactive enzymes
Catalytic sub-unit activated by a regulatory sub-unit.
catalytic subunits are called cyclin-dependent kinases (CDKs)
Regulatory sub-units are called cyclins.

43
Q

What do active CDK/cyclin complexes do?

A

Phosphorylate target proteins.
Phosphorylation results in activation/inactivation of that substrate.
Substrates regulate events in the next cycle phase.

44
Q

What are CDK inhibitors?

A

The cell cycle brakes. E.g INK4A inhibits kinase.

45
Q

What is carcinogenesis?

A

Failure of cell cycle control
Balance between proliferation and apoptosis are disrupted.
Uncontrolled proliferation leads to tumours.

46
Q

What are chemical carcinogens?

A

Chemical carcinogens or their active metabolites react with DNA forming covalently bound products (DNA adducts).
Adduct formation at particular chromosome sites causes cancer.

47
Q

What regulatory pathways are frequently disrupted by cancer?

A
  1. The cyclin D-pRb-E2F pathway

2. p53 pathway

48
Q

What is the role of p53?

A

Maintains the integrity of the genome.
Induced cell cycle arrest at G1
Facilitates DNA repair.
Can induce apoptosis.

49
Q

What happens when the p53 pathway is disrupted?

A

Mutated p53 doesn’t arrest at G1 so the damaged DNA is not repaired.

50
Q

What is a retinoblastoma gene?

A

An anti-oncogene (tumour supressor)

51
Q

What is the inherited form of anti-oncogene mutation?

A

One defective inherited copy of pRb

Somatic point mutation of other copy

52
Q

What is the sporadic form of anti-oncogene mutation?

A

Both hits occur in a single cell.

Takes longer to develop than inherited.

53
Q

What are some examples of inherited cancer syndromes?

A 
Familial retinoblastoma
Familial adenomatous polyposis of colon- 1000s of polyps
Multiple Endocrine Neoplasia 
Neurofibromatosis
Von Hippel-Lindau Syndrome
54
Q

How are proto-oncogenes activated to form oncogenes?

A

Point mutation.

Chromosome rearrangements + translocations.

55
Q

Name some active oncogene products?

A 
Growth Factors
Growth Factor Receptors
Proteins involved in Signal Transduction
Nuclear Regulatory Proteins
Cell Cycle Regulators
56
Q

What are the mechanisms of viral carcinogenesis?

A

Virus genome inserts near a host proto-oncogene.

Viral promoter or other transcription regulation elements cause proto-oncogene over-expression.

Retroviruses insert an oncogene into host DNA causing cell division.

57
Q

What are some DNA viruses that are known to cause cancer in humans?

A

HPV (cervical cancer)
Hepatitis B (liver cancer)
EBV (Burkitt lymphoma)

Year 1 Medicine (37 decks)

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