2.14 - Cancer

Benign and malignant tumours

• Cancer is a disease that arises when changes in a cell lead to abnormal, uncontrolled growth and division.
• These abnormal cells divide far faster than the body needs, building up into a mass of cells called a tumour.
• There are two types of tumour, and they behave very differently.

Benign tumours

• A growth of abnormal cells that stays contained in one area, usually held within a membrane (it is encapsulated).
• It grows until there is no more room, but does not invade or spread to other parts of the body.
• Not normally dangerous, and is not cancer.

Malignant tumours

• A malignant tumour is cancer, and its cells are not held in one place (it is not encapsulated).
• The tumour grows into and invades neighbouring healthy tissues.
• Cells can break off and be carried around the body in the bloodstream.
• Wherever these cells settle, they invade the tissue and grow into new tumours, called secondary tumours.
• Because malignant tumours spread and damage tissue throughout the body, they can be fatal.

Cancer risk factors

• Anyone can develop cancer. Having a risk factor doesn't mean a person will definitely get cancer - it only raises the chance.
• Risk factors fall into two types: lifestyle factors and inherited faulty genes.

Lifestyle risk factors

• Smoking - Strongly linked to lung cancer, and also to mouth, stomach, and cervical cancer
• Obesity - Linked to cancers such as bowel, liver, and kidney cancer
• UV (ultraviolet) radiation - Too much exposure, from the Sun or sunbeds, damages skin cells and increases the chance of skin cancer
• Viral infection - Infection with certain viruses raises cancer risk. Infection with the human papilloma virus (HPV) is linked to cervical cancer, which the HPV vaccine helps protect against
• Carcinogens - Substances or types of radiation that cause cancer, such as ionising radiation

Inherited risk factors

• Not all risk factors are lifestyle choices - some people inherit faulty genes that make them more susceptible to particular cancers.
• For example, mutations in the BRCA genes are linked to an increased chance of developing breast and ovarian cancer.