Cancer is a word that can send shockwaves through a family. In some cases, it is completely treatable, and in others cases, it can change a seemingly healthy person into a very sick one in a matter of months.

Usually cells divide in a very controlled way. The genetic material responds to the environment the cells are in. Some cells die naturally through a process called apoptosis.

When these abnormal cells don’t die off, but multiply and divide instead, tumours can form. Because the cells do not die naturally, they are called immortal.

There are many different forms of cancer, depending on the type of cells that go out of control. Because of this, treatment is also different for different types of cancer.

What do abnormal cells look like?

Normal cells are uniform and arranged in tissues in an orderly manner. When you poke and prod normal tissue, it’s soft. Abnormal cells have a large irregularly shaped nucleus and a relatively small cytoplasm. They have large variations in cell size and shape, disorganised arrangement of cells and poorly defined tissue boundary. The cells lose specialised functions, and many cells are produced quickly. All this means that the resulting tissue is very stiff compared with normal tissue.

What are tumours?

If the cells divide and multiply in one area, they form a tumour or growth. This can cause damage to surrounding parts of the body if its size puts pressure on a body organ or some blood vessels.

Tumours can be benign or malignant. A benign tumour is one where the cells have not spread anywhere else. The doctors can take a sample of the tumour tissue, and this can be looked at through microscope. The characteristics of the outside of the cells show whether they are likely to spread. If this is the case, the tumour is considered malignant. By definition, the term cancer is applied to malignant tumours.

Cancerous cells that have started spreading around the body can continue to multiply and divide in new places.

What causes cancer?

Different cancers have different causes. Some are caused by the presence of particular genes passed down through families, and others are caused by external influences. Often external influences, such as smoking causing lung cancer, are described as risk factors. This is because while there has been found to be a link between smoking and a person getting lung cancer, smoking does not guarantee a person will suffer from lung cancer.

Substances that can cause cancer are called carcinogens. Some of these substances cause cells to mutate, while others cause cells to multiply at a faster rate.

    Published 23 July 2007