茶与癌症.docVIP

Tea and Cancer Introduction Cancer is a major cause of morbidity in the UK with approximately 270,000 newly diagnosed cases, and around 150,000 deaths from cancer each year. It is expected that more than one in three people in England will develop cancer at some stage in their lives. The disease is more likely to develop in later life, with around 75% of deaths from cancer being diagnosed in people over the age of 651. However, although there are fewer deaths from cancer in younger people, cancers cause a greater proportion of deaths: 1 in 3 (37%) deaths in adults aged under 65 years are caused by cancer.1 What is cancer? Cancer is often thought of as a single disease, however in reality it is a term that covers a range of malignant conditions that can affect almost any organ or tissue in the body. Cancer occurs when tissue cells are no longer under the control of normal molecular regulatory processes that usually result in the division, differentiation and ultimately death of these healthy cells. When these control mechanisms become disturbed the cells divide in an uncontrolled and abnormal manner, often failing to differentiate and failing to respond to the usual death signals. In most cancers this uncontrolled growth results in the formation of a tumour. In many cancers the malignant cells will migrate from their primary tissue of origin to secondary sites creating secondary tumour growths or ‘metastases’. The lethal effects of both primary and secondary cancers is due to the compression of healthy cells, often killing them, so preventing the normal functioning of major organs. Causes of cancer The vast majority of cancers are caused by a disorder of cellular genetic material. Damage to the DNA within the cells maybe as a result of environmental factors such as radiation, chemical carcinogens and some viruses. Certain risk factors are associated with different types of cancer, and some of these are modifiable1:- Smoking is the greatest known risk factor for cance