Leukaemia Flashcards

1
Q

What is the most common cancer in the 15-24 age group?

A

Cancers of the blood

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2
Q

What is the literal meaning of leukaemia?

A

White blood

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3
Q

Where does the problem exist in leukaemia?

A

In the bone marrow (not all patients have abnormal cells in the blood)

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4
Q

What does leukaemia result from?

A

A series of mutations in a single lymphoid or myeloid stem cell

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5
Q

What are the consequences to the progeny of the mutated cell?

A

These mutations lead to progeny of that cell to show abnormalities in proliferation, differentiation or cell survival leading to steady expansion of the leukaemic clone

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6
Q

Which cells can be affected in leukaemia?

A
Pluripotent haematopoietic stem cell 
Myeloid stem cell  
Lymphoid stem cell  
Pre B lymphocyte  
Pro T lymphocyte
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7
Q

What are the equivalent terms for ‘benign’ and ‘malignant’ in terms of leukaemia?

A

Leukaemias that behave relatively benignly are CHRONIC

Leukaemias that behave in a malignant manner are ACUTE– the disease is very aggressive

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8
Q

What are the four main types of leukaemia?

A

Acute lymphoblastic leukaemia
Acute myeloid leukaemia
Chronic lymphocytic leukaemia
Chronic myeloid leukaemia

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9
Q

Explain the significance of the terms acute lymphoblastic leukaemia and chronic lymphocytic leukaemia.

A

In ALL the cells are immature – they are lymphoblasts

IN CLL the cells are mature lymphocytes

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10
Q

What are the important leukaemogenic mutations that have been recognised?

A
  1. Mutation in a known proto-oncogene
  2. Creation of a novel gene e.g. chimeric or fusion gene
  3. Dysregulation of a gene when translocation brings it under the influence of a promoter or enhancer of another gene
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11
Q

State some inherited or other constitutional abnormalities that can contribute to leukaemogenesis.

A
  1. Down syndrome
  2. Chromosomal fragility syndromes
  3. Defects in DNA repair
  4. Inherited defects in tumour suppressor genes
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12
Q

What are some identifiable causes of leukaemogenic mutations?

A
  1. Irradiation
  2. Anti-cancer drug
  3. Cigarette smoking
  4. Chemicals e.g. benzene
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13
Q

What type of cell is seen in abundance in acute myeloid leukaemia?

A

Immature myeloid cells – the cells continue to proliferate but they no longer mature so there is a build up of immature cells (myeloblasts) in the bone marrow, which spread to the blood

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14
Q

Explain how acute leukaemia leads to bone marrow failure.

A

The leukaemic cells crowd out the normal cells in the bone marrow leading to a decrease in the production of other end cells e.g. neutrophils, monocytes, platelets

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15
Q

What do the responsible mutations normally affect in AML?

A

Transcription factors – the transcription of multiple genes is affected
Often the product of an oncogene prevents the normal function of theprotein encoded by its normal homologue
This leads to changes in cell kinetics and cell functions

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16
Q

What do the responsible mutations normally affect in CML?

A

A gene encoding a protein in the signalling pathway between a cell surface receptor and the nucleus
The protein encoded may be a membrane receptor or a cytoplasmic protein

17
Q

Describe the nature of the leukaemic cells in CML.

A

These are mature lymphocytes – their cell kinetics and function are not as seriously affected as they are in AML but the cells do become independent of external signals, there are alterations in the interaction with stroma and there is reduced apoptosis so that cells survive longer and the leukaemic clone expands progressively

18
Q

How is the production of end cells affected in AML and CML?

A

AML – decrease in the production of end cells

CML – increase in the production of end cells

19
Q

What are the metabolic effects of leukaemic cell proliferation?

A
Hyperuricaemia  
Renal failure  
Weight loss  
Low grade fever  
Sweating
20
Q

Which type of leukaemia increases the risk of intraventricular haemorrhage and why?

A

Acute promyelocytic leukaemia (APML) – this is associated with DIC so the platelet count and fibrinogen are low leading to increased risk of fatal haemorrhage

21
Q

How can leukaemia cause proliferation of the gums?

A

Infiltration of leukaemic cells and monocytes can lead to inflammation of the gums
There will be small haemorrhages due to thrombocytopenia

22
Q

What does epidemiology suggest that B lineage acute lymphoblastic leukaemia may result from?

A

It may result from delayed exposure to a common pathogen

23
Q

What are some factors that relate to risk of leukaemia?

A

Family size, new towns, socio-economic class, early social interactions

24
Q

What can leukaemias in infants and young children result from?

A

Irradiation in utero

In utero exposure to certain chemicals

25
Q

What are the clinical features of acute lymphoblastic leukaemia?

A
Bone pain  
Hepatomegaly  
Splenomegaly  
Lymphadenopathy 
Thymic enlargement  
Testicular enlargement  
These all result from the accumulation of abnormal cells
26
Q

What are some clinical features of acute lymphoblastic leukaemia that result from the crowding out of normal cells

A

Caused by anaemia – fatigue, lethargy, pallor, breathlessness
Caused by neutropenia – fever and other features of infection
Caused by thrombocytopenia – bruising, petechiae, bleeding

27
Q

What investigations are performed in acute lymphoblastic leukaemia?

A
Blood count and film  
Check of liver function and renal function and uric acid  
Bone marrow aspirate  
Cytogenetic/molecular analysis  
Chest X-ray
28
Q

What are the uses of cytogenetic and molecular genetic analysis in ALL?

A

It is useful for managing the individual patient because it gives us information about prognosis
It permits the discovery of leukaemogenic mechanisms

29
Q

What are the implications of hyperdiploidy in in the cytogenetic analysis of ALL?

A

Good prognosis

30
Q

What features of the cytogenetic analysis are associated with a poor prognosis?

A

Chromosomal translocations resulting in the formation of a bad fusion gene

31
Q

What translocation causes ALL? State the fusion gene.

A

Translocation between chromosome 12 and chromosome 21

Fusion gene: ETV6-RUNX1 on chromosome 12

32
Q

What technique is used to detect the fusion genes in ALL?

A

Fluorescence in situ hybridisation (FISH)

33
Q

What are the treatment options for ALL?

A

Supportive: red cells, platelets, antibiotics
Systemic chemotherapy
Intrathecal chemotherapy

34
Q

What % of all cancers are of the blood

A

5%

- main causes of cancer death in those aged 1-34

35
Q

What would you see on the CT of leukaemia ?

A

Intraventricular haemorrhage

36
Q

What happens to the function of the immune system in CLL?

A

loss of normal function

37
Q

At what age is the highest incidence of ALL?

A

4

largely a disease of children

38
Q

Give some acute lymphoblastic leukaemia—leukaemogenic mechanisms

A
  1. Formation of a fusion gene
  2. Dysregulation of a proto-oncogene by juxtaposition of it to the promoter of another gene, e.g. a T-cell receptor gene
  3. Point mutation in a proto-oncogene
39
Q

Give an example of dysregulation in ALL

A

t(10;14)(q24;q11)—the TCL3 gene is dysregulated by proximity to the TCRA gene