cancer 14 Flashcards
what is leukemia?
- Leukaemia is the cancer of the blood
- Leukaemia results from a series of mutations in a single lymphoid or myeloid stem cell
- These mutations lead the progeny of that cell to show abnormalities in proliferation, differentiation or cell survival
- this leads to the steady expansion of the leukaemic clone, it takes over from normal cells
.what is the epidemiology of leukemia?
- 5% of all cancers are cancers of the blood
- Blood cancers are the most common cancers in men and women aged 15-24 and the main cause of death in 1-34
show which cells might be involved:
Leukemia might affect
- Pluripotent hematopoietic stem cell.
- Myeloid/lymphoid stem cell.
- Pro-/Pre-T/B lymphocyte.
why is leukemia different from other cancers?
- most cancers exist as a solid tumor
- instead, leukemic cells replace the normal bone marrow cells and circulate freely in the bloodstream
- Normal hematopoietic stem cells circulate in the blood and both the stem cells and the cells derived from them can enter tissues, and normal lymphoid stem cells recirculate between tissues and blood.
how do normal hematopoietic stem cells and lymphoid stem cells circulate?
- Normal haematopoietic stem cells circulate in the blood and both the stem cells and the cells derived from them can enter tissues
- normal lymphoid stem cells recirculate between tissues and blood.
can the terms of invasion and metastasis be applied?
can the words benign and malignant be used?
- they cannot as blood cells always travel around the body
- Benign leukaemia = chronic
- Malignant = acute (aggressive and quick death)
How is leukemia classified?
- Leukemia can be acute or chronic
- it can also be lymphoid or myeloid
- Lymphoid can be B or T lineage
- Myeloid can be any combination of granulocytic, monocytic, erythroid or megakaryocytic
what are the final 4 classes of leukemia?
- ALL – Acute Lymphoblastic Leukaemia
- CLL – Chronic Lymphocytic Leukaemia.
- AML – Acute Myeloid Leukaemia.
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why does leukemia occur?
- Leukemia is an acquired genetic disease arising from somatic mutation
- Leukemia results from a series of mutations in a single stem cell
- Some mutations result from identifiable or unidentifiable oncogenic influences
- others are random errors that accumulate over time
what are the improtant leukaemogenic mutations ?
- Mutation in a known proto-oncogene - Creation of a novel gene, e.g. a chimaeric or fusion gene - Dysregulation of a gene when translocation brings it under the influence of the promoter or enhancer of another gene - Loss of function of a tumour-suppressor gene resulting from a deletion or mutation of gene, this makes a leukaemia more aggressive - If there is a tendency to increased chromosomal breaks, the likelihood of leukaemia is increased - if the normal repair mechanism is affected then the likelihood of leukaemia is increased
- which genetic conditions increase the likelihood of leukemia?
- Down’s syndrome Chromosomal fragility syndromes Defects in DNA repair Inherited defects of tumour-suppressor genes
what environmental factors contribute to leukaemia?
Irradiation
Anti-cancer drugs
Cigarette smoking
Chemicals—benzene
what kind of mutation causes leukemia?
- results from somatic mutation - Mutation in germ cells may bring favourable, neutral or unfavourable characteristics to the species - if negative then might cause leukaemia
what does myeloid mean?
myeloid = overall generic term
blood cells that arise from a progenitor cell for granulocytes, monocytes, erythrocytes, or platelets
what is the nature of acute myeloid leukemia?
- in acute myeloid leukemia cells continue to proliferate but they no longer mature so there is a build up of the most immature cells
- Failure of production of normal functioning end cells such as neutrophils, monocytes, erythrocytes, platelets
- the mutations often affect the transcription factors so transcription of genes is affected