The cancer cell

A cancer cell is a cell that divides (makes a copy of itself) and reproduces abnormally. It has the potential to spread throughout the body although it does not always do this.

Normally a cell grows and reproduces according to the strict instructions contained in its genetic material. It behaves in a controlled manner and follows the following rules:

• It dies if it becomes damaged
• It reproduces a limited number of times before dying
• It responds to chemical messages from other cells which tell it what to do
• It dies if it travels to the wrong place in the body.

Sometimes, when a cell divides the process goes wrong. When this happens the cell usually self-destructs. Cancer forms when the abnormal cell does not die but carries on dividing. It does not follow any of the normal rules or behave in a controlled way.

Billions of copies of the faulty cell are made which form a lump, or tumour. From this tumour, cancer cells can break away and begin to grow in another part of the body. This is a secondary tumour.

Tumours can be:

Benign (non-cancerous) - which means they do not have the ability to spread to other parts of the body. They can cause a problem if they grow too large and press on surrounding parts of the body, interfering with the way they work.

Malignant (cancerous) - these tumours can spread to other parts of the body. These tumours are called 'metastases', where the original cancer has 'metastasised'. It is the ability to spread that is the difference between the cells in a benign and malignant tumour. Many doctors use the word ‘malignant’ to mean cancer.

Malignant tumours are classified according to how far they have spread in the body (their stage) and by the type of cancer cells they contain (their grade).