What is cancer?
Cancer is caused by damage to the genes in your cells. Most cancers only happen when several genes are damaged in the same cells. This kind of damage accumulates over many years and this is why cancer usually happens in older people. Cancer is rare in children.
Genes are made up of DNA and when a cell splits and grows into two cells, this DNA must be copied carefully to make sure that both new cells receive the correct number of genes.
If certain genes become damaged then the cell may not know how to stop making more cells. The damage occurs in genes that help cells grow and become two cells; genes that normally tell cells to stop copying themselves; or genes that check that DNA is copied correctly.
The tumour, coloured green, is encouraging blood vessels, in red, to come and supply it with blood
If a cell has a major mistake in its DNA then it usually dies by apoptosis or is killed by the immune system. The cells not killed by these two methods will go on multiplying to make more cells, copying the mistake every time.
Eventually these cells will become immortal, and will carry on multiplying uncontrollably. If the immortal cells accumulate more genetic damage they grow into a tumour. This tumour can only grow to a few millimetres wide unless it has a blood supply.
Cancer cells can instruct the body to make them a new blood supply. The tumour can then grow bigger and bigger and the cancer cells begin to invade the surrounding tissue and spread to other organs using the blood vessels and lymph circulation.
Normal tissue in the cervix is very organised
It may take a long time for a cancer cell to accumulate mistakes, copy them and become cancerous. But there are certain factors that increase the likelihood of mistakes being made. These are cancer-causing agents such as in cigarette smoke, sunshine rays, and other chemicals in the environment.
Mistakes in your DNA will be collected over your lifetime making it more likely that you will get cancer in old age, especially if you smoke or don't use a sunscreen.
Some people are born with a mistake in their genes that makes them more likely to accumulate other mistakes and get cancer quite early in life.
