Introduction to Leukaemia Flashcards

1
Q

What is leukaemia

A

Malignant disorders of haematopoietic stem cells characteristically associated with an increased number of white cells in bone marrow or/and peripheral blood

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2
Q

What are haematopoetic stem cells

A

Multipotent- can give rise to cells of every blood lineage

Self maintaining- a stem cell can divide to produce more stem cells

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3
Q

What are progenitor cells

A

Can divide to produce many mature cells
But cannot divide indefinitely
Eventually differentiate and mature

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4
Q

What is the difference between undifferentiated and committed progenitor cells

A

Undifferentiated (multipotent): you cannot tell the difference between them morphologically because they do not show the characteristics of mature cells

Committed (unipotent): already committed as to what they will become when they generate mature cells

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5
Q

How does leukaemia arise

A

It is a clonal disease- all the malignant cells derive from a single mutant stem cell
It form sit sown progenitor cells

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6
Q

What is the incidence of leukaemia

A

The higher incidence rate in the elderly, increases with ageing

Childhood cases are rising now at 31%

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7
Q

what are the initial symptoms of leukaemia

A

Typically first presents with symptoms due to loss of normal blood cell production:

  • Abnormal bruising-commonest
  • Repeating abnormal infection
  • Sometimes anaemia
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8
Q

How can we clinically diagnose leukaemia and what does each test show

A
  • Peripheral blood blasts test (PB): to check for presence of blasts and cytopenia. >30% blasts are suspected of acute leukaemia.
  • Bone marrow test/biopsy (BM): taken from pelvic bone and results compared with PB.
  • Lumbar puncture: to determine if the leukemia has spread to the cerebral spinal fluid (CSF).
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9
Q

How can we diagnose leukaemia pathologically

A
  • Cytomorphology
  • Immunophenotyping
  • Next-generation sequencing
  • Flow cytometry
  • Fluorescence in situ hybridation (FISH)
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10
Q

What are the predisposing factors for leukaemia

A
  • Genetic risk factors
  • Lifestyle-related
  • Uncertain, unproven or controversial factors
  • Environmental risk factors
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11
Q

How can genetic risk factors cause disease

A

NOT usually hereditary
(except for some cases of Chronic Lymphocytic Leukaemia (CLL))

Some rare genetic diseases may predispose to leukaemia, e.g. Fanconi’s anaemia, Down’s syndrome

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12
Q

what genetic risk factors that cause leukaemia

A
  • Gene mutations involving oncogenes (activation) or/and tumour suppressors (inactivation).
  • Chromosome aberrations:
    Translocations (e.g. BCR-ABL in CML).
    Numerical disorders (e.g. trisomy 21-Down syndrome).
  • Inherited immune system problems (e.g. Ataxia-telangiectasia, Wiskott-Aldrich syndrome).
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13
Q

what environmental risk factors that cause leukaemia

A

Radiation exposure:

  • acute radiation accidents
  • atomic bomb survivors

Exposure to chemicals and chemotherapy:

  • Cancer chemotherapy with alkylating agents (e.g. Busulphan)
  • Industrial exposure to benzene

Immune system suppression:

  • e.g. After organ transplant
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14
Q

what lifestyle-related risk factors that cause leukaemia

A
  • Smoking
  • Drinking
  • Excessive exposure to sun
  • Overweight
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15
Q

what controversial risk factors that cause leukaemia

A
  • Exposure to electromagnetic fields
  • Infections early in life
  • Mother’s age when the child is born
  • Nuclear power stations
  • Parent’s smoking history
  • Foetal exposure to hormones
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16
Q

What are the 4 types in leukaemia classifaction

A
  • Acute lymphoid leukaemia
  • Chronic lymphoid leukaemia
  • Acute myeloid leukaemia
  • Chronic myeloid leukaemia
17
Q

Describe acute leukaemia

A

Acute disease: rapid onset and short but severe course.

Acute leukaemia:
Undifferentiated leukaemia
Characterised by uncontrolled clonal and accumulation of immature white blood cells (-blast)

18
Q

Describe chronic leukaemia

A

Chronic disease: persisting over a long time.

Chronic leukaemia:
Differentiated leukaemia
Characterised by uncontrolled clonal and accumulation of mature white blood cells (-cyte)

19
Q

Compare acute and chronic leukaemia

A

Acute:

  • Mainly in children
  • Sudden onset
  • Weeks to months duration
  • Variable WBC count

Chronic:

  • Mainly in middle age and elderly
  • Insidious onset
  • Years duration
  • High WBC count
20
Q

What is the incidence rate of acute leukaemia

A
  • 31% of cancer in children is leukaemia
  • Of that 75% is acute lymphoid and 25% are acute myeloid
21
Q

What is acute leukaemia characterised by

A

Characterized by a large number of lymphoblasts (ALL) or myeloid blasts (AML) in bone marrow and blood- “undifferentiated leukaemia”

22
Q

What are the typical symptoms of acute leukaemia due to bone marrow suppression

A
  • Thrombocytopenia: purpura (bruising), epistaxis (nosebleed), bleeding from gums.
  • Neutropenia: Recurrent infections, fever.
  • Anaemia: lassitude, weakness, tiredness, shortness of breath
23
Q

How can we treat acute leukaemia

A

Lymphoblastic:

  • Chemotherapy. Long-term side effects are rare

Myeloblastic:

  • Chemotherapy, monoclonal antibodies (immunotherapy) +/- allogeneic bone marrow transplant
24
Q

What is chronic leukaemia characterised by

A

Characterised by an increase number of differentiated cells -“differentiated leukaemia”

25
Q

What are the symptoms of chronic lymphocytic leukaemia

A

Recurrent infections due to neutropenia, and suppression of normal lymphocyte function, anaemia, thrombocytopenia, lymph node enlargement, hepatosplenomegaly

26
Q

What are the symptoms of chronic Myeloid/granulocytic leukaemia

A

Often asymptomatic and discovered through routine blood tests

27
Q

How can we treat chronic lymphocytic leukaemia

A

Regular chemotherapy to reduce cell numbers

28
Q

How can we treat chronic Myeloid/granulocytic leukaemia?

A

Targeted therapy: Imatinib

29
Q

What is the BCR-ABL oncogene

A
  • 95% of cases of CML have a detectable Philadelphia chromosome (Ph’)
  • There is a break in chromosomes 9 and 22
  • The broken sections swap and fuse on the other chromosome
  • This brings the ABL and BCR genes together on chromosome 22 causing the Philadelphia chromosome
30
Q

How does this oncogenes cause CML

A
  • BCR: encodes a protein that needs to be continuously active
  • ABL encodes a protein tyrosine kinase whose activity is tightly regulated (auto-inhibition)
  • BCR-ABL protein has constitutive (unregulated) protein tyrosine kinase activity

Unregulated BCR-ABL= tyrosine kinase activity that causes:
- Proliferation of progenitor cells in the absence of growth factors
- Decreased apoptosis
- Decreased adhesion to bone marrow stroma

31
Q

What are the applications of the BCR-ABL oncogene

A
  • Diagnosis: 95% of cases of CML have a detectable Ph’ chromosome.
  • Detection of minimal residual disease.
  • Therapy: Drugs that specifically inhibit BCR-ABL. e.g. Imatinib (Glivec®, STI571). Cases negative for BCR-ABL require different therapy
32
Q

How can targeted therapy be used in treating CML

A

Imatinib (Glivec®, STI571) is a small molecule inhibitor that targets specifically Abl –CML treatment:

  • Diagnosis: 95% of cases of CML have a detectable Ph’ chromosome.
  • Used for detection of minimal residual disease
  • Remission induced in more patients,
    with greater durability and fewer
    side effects
  • Some patients become drug resistant
33
Q

How has targeted therapy worked in CML

A
  • Positive outcomes also in the treatment of gastrointestinal stromal tumours and SCLC.