The uncontrolled growth of cells forms a lump called a tumour. Some tumours are benign and may not cause any problems. Others however are malignant. They can invade into other body tissues and cause severe damage. It is these malignant tumours that we call cancer.

There are over 200 different types of cancer and they can occur anywhere in the body.

When cells begin to grow in an uncontrolled way, they form a lump called a tumour. Some tumours stay within one specific area. They do not spread into surrounding tissues and may not cause any problems. If it is easy to do so, these benign tumours are usually removed by surgery. There are usually no further problems.

Cancers are dangerous types of growths called malignant tumours. In this type of tumour the cells invade the surrounding tissues. Cancer cells can break off and be carried to different parts of the body in the bloodstream. This spreads the cancer throughout the body where it can cause serious damage and eventually death.

• Step 1. The primary tumour develops as a group of cells that are growing out of control.
  
  
• Step 2. The tumour gets bigger and stimulates blood vessels to supply it from the surrounding tissues.
  
  
• Step 3. Tumour cells squeeze into blood and lymph vessels and move to other parts of the body
  
  
• Step 4. When the tumour cells reach other areas of the body, like the liver and lungs, they begin to grow and form secondary tumours. If they are not treated quickly enough, the damage that these secondary tumours cause can be fatal.