The transformation of normal, healthy cells into diseased cancer cells is directly attributable to genetic damage causing DNA abnormalities that alter cell growth, proliferation and survival.6, 8, 9 These abnormal genetic changes are termed mutations and may take the form of any of a number of alterations in the DNA sequence of a cell. Mutations may include point mutation, deletion, translocation, and inversion. The eventual impact of a mutation depends on where in the genetic sequence the error occurs.
Increasingly, research is identifying the specific genes and the mutations of the genes that are implicated in the transformation of a normal cell into a cancer cell. The key role played by two groups of cancer genes, proto-oncogenes and tumour suppressor genes, in the malignant transformation of cells is now evident.6, 7, 9 Examples of such mutations include the up regulation of HER2 in breast cancer, the BCR-ABL translocation in chronic myeloid leukaemia, epidermal growth factor receptor in lung cancer, and C-KIT mutations in gastrointestinal stromal tumours.21
Genetic mutations that lead to the malignant transformation of cells and the development of cancer may be acquired or hereditary. Genetic damage resulting from exposure to carcinogens, whether exogenous or endogenous, is classified acquired mutation. Inherited abnormal alterations in the genetic sequence that predispose individuals to cancer are known as hereditary mutations.6, 8
Outline the key differences between the impact of hereditary and acquired genetic mutations in the development of cancer.
Differentiate point mutations from translocations.
Summarise the role of proto-oncogenes and tumour suppressor genes and compare this to the role that their mutated counterparts play in the development of cancer.
Define the following genetic terms:
Identify how the following genes contribute to the development of specific cancers and impact on a person's cancer journey:
- BRCA 1/2
In the case of chronic myeloid leukaemia, identify the location of the mutation that results in the formation of an abnormal receptor and the resultant progression of disease.
Access the website for the Centre for Genetics Education22 and outline the information, resources and supportive care the SCN may provide for the person who is concerned they have a family history of cancer.