What is cancer?

Cancer is a term used for diseases in which abnormal cells divide without control and are able to invade other tissues. ​Cancer cells can spread to other parts of the body through the blood and lymph systems. Cancer is not just one disease but many diseases. There are more than 200 different types of cancer.

 

What causes cancer?

Our bodies are made up of millions of cells and for a cancer to start, certain changes take place within the genes of a cell or a group of cells. Cancer starts when cells in a part of the body start to grow out of control. Cancer cell growth is different from normal cell growth. Instead of dying, cancer cells continue to grow and form new, abnormal cells.

 

Cancer cells can also invade other tissues, something that normal cells can’t do. Growing out of control and invading other tissues are what makes a cell a cancer cell. Cells become cancer cells because of changes to their DNA (deoxyribonucleic acid). DNA is in every cell and contains thousands of genes, which are coded messages that tell the cell how to behave. 

 

In a normal cell, when DNA is damaged the cell either repairs the damage or dies. In cancer cells, the damaged DNA is not repaired, and the cell doesn’t die like it should. Instead, the cell goes on making new cells that the body doesn’t need. These new cells all have the same damaged DNA as the first cell does. In most cases, these cells go on to form tumors. Some types of cancer, called leukaemia, start from blood cells. They don't form solid tumours. Instead, the cancer cells build up in the blood and sometimes the bone marrow.

 

Sometimes, it is possible to have inherited an abnormal DNA (this can be passed on from parents) but most of the time DNA damage are caused by mistakes that happen when cells are dividing or in some cases by external factors such as cigarette smoking. That being said, doctors often do not know exactly what causes any one person’s cancer or why one person develops cancer and another does not.

 

Some risk factors for cancer

It is usually not possible to know exactly why one person develops cancer and another doesn’t.

However, research has shown that certain risk factors may increase a person’s chances of developing cancer.These are the most common risk factors for cancer:

 

• Tobacco

• Growing older

• Alcohol

• Family history of cancer

• Poor diet, lack of physical activity, or being overweight

• Some viruses, bacteria and parasites; such as HPV

• Certain hormones