Cancer and carcinogens
Cells grow then divide by A type of cell division which produces daughter cells identical to the parent. only when we need new ones. This is when we're growing or need to replace old or damaged cells.
When a cell becomes A disease caused by normal cells changing so that they grow and divide in an uncontrolled way. The uncontrolled growth causes a lump called a tumour to form., it begins to grow and divide uncontrollably. New cells are produced even if the body does not need them. A group of cancerous cells produces a growth called a The lump of cells formed as a result of uncontrolled cell division..
Types of tumour
Tumours are of two types called A tumour that is not cancerous and cannot spread to other areas of the body. and A fast-growing tumour that is cancerous and can invade and spread to other areas of the body.:
| Type of tumour | Characteristics |
| Benign | Grow slowly. Usually grow within a membrane, so can easily be removed. Do not invade other parts of the body. |
| Malignant | Grow quickly. Invade neighbouring tissues and can spread to other parts of the body in the bloodstream. As the tumour grows, cancer cells detach and can form secondary tumours in other parts of the body. This process is called metastasis. |
| Type of tumour | Benign |
|---|---|
| Characteristics | Grow slowly. Usually grow within a membrane, so can easily be removed. Do not invade other parts of the body. |
| Type of tumour | Malignant |
|---|---|
| Characteristics | Grow quickly. Invade neighbouring tissues and can spread to other parts of the body in the bloodstream. As the tumour grows, cancer cells detach and can form secondary tumours in other parts of the body. This process is called metastasis. |
The diagram shows how cancer cells can invade surrounding tissue:
Image caption, Growth of a malignant tumour by mitosis
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Cancer cells are undifferentiated – they do not carry out their normal function.
At some point, secondary tumours may develop.
Image caption, The spread of a tumour by metastasis
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What causes cancer?
There are genetic factors that increase the likelihood of developing some cancers. Chemicals and other agents that can cause cancer are called A chemical or other agent that causes cancer..
Carcinogens cause cancer by damaging Deoxyribonucleic acid. The material inside the nucleus of cells, carrying the genetic information of a living being.. Carcinogens cause A random and spontaneous change in the structure of a gene, chromosome or number of chromosomes. to occur. A single mutation will not cause cancer. Several are required for this to occur. For this reason, we are more likely to develop cancer as we get older.
Something that increases the likelihood of developing a disease is called a risk factor. There are several risk factors for various types of cancers including:
Lifestyle factors:
- viruses linked with cancer, such as the human papilloma virus (HPV), being spread from person to person through sexual intercourse
- the chemical carcinogens in cigarette smoke increasing the risk of lung cancer
- alcohol intake is linked with certain cancers
- exposure to A high energy part of the electromagnetic spectrum associated with sunburn and skin cancer., part of which is Radiation that is able to remove electrons from atoms or molecules to produce positively charged particles called ions., during sunbathing or outdoor activities, leading to the development of skin cancers
- diet, including fat and salt intake, increases the risk of cancer
Industrial and environmental factors at work:
- exposure to ionising radiation increases the risk factor
- exposure to chemical carcinogens
There are also genetic risk factors for some cancers.