Cancer: A bunch of cells acting as killing machine

What is cancer ?

Cancer starts in our cells. Cells are tiny building blocks that make up the organs and tissues of our body. Usually, these cells divide to make new cells in a controlled way. This is how our bodies grow, heal and repair.

Sometimes, this goes wrong and the cell becomes abnormal. The abnormal cell keeps dividing and making more and more abnormal cells. These cells form a lump, which is called a tumour.

Not all lumps are cancerous.

  • A lump that is not cancerous (benign) cannot spread to anywhere else in the body.
  • A lump that is cancer (malignant) can grow into surrounding tissue.
    These cells sometimes break away from the primary cancer and travel through the blood or lymphatic system to other parts of the body. These cells that spread and develop into a tumour somewhere else in the body are called a secondary cancer.
Who get cancer ?

Each year over 330,000 people are diagnosed with it in the UK. In this section are some facts about how it affects different age groups of people and the most common types of cancer people get.


It has been estimated that more than one in three people (33%) will develop at some point in their lifetime.

This can occur at any age, but the risk of developing cancer increases with age. It isn’t common in children or young people.

  • More than a third (36%) of all are diagnosed in people aged 75 or over.
  • Over half (53%) of all  occur in people aged 50-74.
  • About 1 in 10 (10%) of  are diagnosed in people aged 25-49.
  • Less than 1 in 100 (1%) of  are diagnosed in teenagers and young adults aged 15-24.
  • Less than 1 in 100 (1%) of  are diagnosed in children aged 14 or under.
Common cancers

Some are very common and others are very rare. The most recent statistics for the UK (from 2011) show that for men the most common cancer is prostate (25% of all cancers in men), followed by lung (14%), colon and rectal (14%) and bladder (4%).

For women, the statistics show that the most common are breast  (30%), lung  (12%), colon and rectal (11%) and womb (5%).

Nearly a third (30%) of all cancers diagnosed in children are leukaemia.

Teenagers and young people (aged 15-24) are more likely to be diagnosed with a lymphoma (21%) or a germ cell tumour (15%) like testicular cancer.

The most common types of cancer diagnosed in adults aged 25-49 are breast cancer, melanoma, colon and rectal, testicular and cervical cancer.

Lifestyle and cancer

There are over 200 different types of cancer. We don’t know the cause of most of these, but we know about some of the risk factors that can increase or influence a person’s risk. Increasing age is a risk factor that we can’t do anything about. But we can make lifestyle choices about some of the other risk factors, such as:

  • stopping smoking
  • eating a balanced diet
  • avoid becoming overweight, or if you are overweight, try to reduce your weight
  • cutting down our alcohol intake
  • getting regular exercise.
  • We’re getting better at recognising and treating, so today many people with cancer can be cured. Even if a cancer can’t be cured, it can often be controlled with treatment for months or years.

We have information on all the main types of cancer and on some of the rarer cancers

How is cancer treated ?

Some  treatments treat a particular area of the body. These are called localised treatments.

  • Surgery. An operation to remove the tumour is the main treatment for many types. It is usually used for cancers that are in one area of the body.
  • Radiotherapy. High energy x-rays are used to destroy the cancer cells. By targeting the area affected by cancer, there is as little harm as possible to the normal cells.
    Other treatments treat the whole body. These are called systemic treatments.
  • Chemotherapy. This uses anti-cancer (cytotoxic) drugs to destroy cancer cells. There are many different chemotherapy drugs. Which you are given depends on the type of cancer you have.
  • Hormonal therapy. These therapies reduce the level of hormones in the body or block the hormones from reaching these cells. This can stop the growing.
  • Targeted therapies. These destroy these cells, usually by interfering with the ability to grow or survive.

It’s quite common for a combination of these treatments to be used. Many of these can cause side-effects. You may find our information on making treatment decisions helpful.

We also have further information about types of  treatment and understanding your diagnosis.

You can find the most relevant information by selecting a cancer type using the options at the top of this page or by browsing the full list of cancer types.


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