Basically, cancer happens when cells in your body start growing at an uncontrolled rate, and eventually this forms a tumour. These tumours can spread through your body in your bloodstream, or in what’s called the ‘lymphatic system’ (which is part of the immune system) and invade cells elsewhere, causing them to grow out of control and turn into tumours too.
Cancer is a group of many related diseases that all have to do with cells. Cells are the very small units that make up all living things, including the human body. Cancer happens when cells that are not normal grow and spread very fast. Normal body cells grow and divide and know when to stop growing. Unlike these normal cells, cancer cells just continue to grow and divide out of control and don’t die when they’re supposed to. Cancer cells usually group or clump together to form tumors. A growing tumor becomes a lump of cancer cells that can destroy the normal cells around the tumor and damage the body’s healthy tissues and this is what can make someone very sick.