How does a cancer start genes and cancer
Whilst there are many different types of cell with as many different functions, all cells have some basic similarities. They have a centre called a nucleus and inside this structure is the DNA, which makes the cells genes.
These genes control the activity of the cell. We now know that cells in a tumour descend from just one initial cell which at some point (usually decades before the tumour is detected) starts a programme of unsuitable growth. This is because some of the information carried in the cells genes has been altered or damaged.
The transformation into a cancer cell comes about through the step-by-step accumulation of a series of genetic alterations or mutations in those particular genes that replicate this growth advantage. Hundreds of genes have a role to play in this process in the normal cell and hundreds of genes have the potential to be damaged in the cancer cell.
How does a cancer spread?
Cancers spread by invading the surrounding tissue until they reach a blood or lymph vessel. Small groups of cells may then break off the original tumour and be carried by the blood or lymph to another part of the body.
A cancer that has spread is said to have metastasized.
Types of cancers
All of the various cell types of the body can grow into a cancer.
| Cancers that derive from different cell types have distinct names to denote the type of cell involved: - a carcinoma is a cancer that has developed from epithelial cells these cells line the digestive tract and make up organs such as the liver, kidney and pancreas. These are the most common type of cancers
- a sarcoma is a cancer that has developed from cells making up either muscle, nerves or blood vessels.
- a lymphoma is a cancer that has developed from cells in a lymph gland
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Cancers from different cell types can behave very differently.
| They may: - grow faster or slower
- produce different symptoms to each other
- respond differently to the same treatment
- be more or less likely to spread to a specific part of the body
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All of these factors are important in the diagnosis and treatment of each type of cancer.
03/06/2009
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