Cancer explained

What is cancer?#

Cancer is a disease of the cells. Cells are the basic building blocks of the human body, which is made up of many different types of cells, such as bone, skin and blood cells. The body constantly makes new cells to help us grow, replace old cells and heal injuries.

Sometimes this process goes wrong and a cell becomes abnormal. The abnormal cell keeps dividing, making more abnormal cells. These cells can gather together and form a lump called a tumour.

There are two kinds of tumour:

• Benign tumours are not cancer. They do not spread to other parts of the body.
• Malignant tumours are cancer. They can spread to other parts of the body.

Where can cancer start?#

Because the body is made up of cells, cancer can start anywhere. Some common places for cancer to start include the skin, bowel, breasts, prostate and lungs.

The place where the cancer first starts is called the ‘primary cancer’. Sometimes doctors can’t find where the cancer first started; this is called ‘cancer of unknown primary’.

Can cancer spread?#

Sometimes cancer cells move to other parts of the body. Cancer that has spread and developed into a tumour somewhere else in the body is called a ‘secondary cancer’ or ‘metastasis’.

How do you get cancer?#

Cancer can happen to anybody. Some things put people at a greater risk of getting cancer, including:

• getting older (half of all cancers are diagnosed in people aged 75 or over)
• smoking tobacco
• drinking too much alcohol
• not doing enough exercise
• eating unhealthy food
• being overweight
• too much sun
• family history
• some viruses, such as the human papillomavirus (spread by sex)
• some chemicals and asbestos

Cancer is not contagious#

People cannot catch cancer from someone who has it. It is safe to be near someone who has cancer.

How common is cancer?#

Cancer is common. Many cancers can be treated by a doctor if they are found early. Screening saves lives because it can find cancer earlier, when it is easier to treat. Screening programs exist for cancers such as breast, bowel and cervical cancer.

How is cancer found (diagnosed)?#

Sometimes doctors find cancer because a person is feeling unwell and has symptoms. Cancer can also be found during routine screening to check your health. Not everyone with symptoms has cancer, but it is important to know what is normal for your body and to see your doctor straight away if you notice changes such as:

• breast changes – lumpiness, a thickened area, unusual nipple discharge, a nipple that turns inwards, or a change in shape, colour or pain
• lumps, sores or ulcers that don’t heal
• skin changes – moles that change shape, size or colour, or that bleed
• a cough that won’t go away
• finding it hard to breathe, or voice changes
• losing weight without trying
• nausea or vomiting that doesn’t go away
• diarrhoea or constipation that doesn’t go away or that you can’t explain
• for women, loss of blood from the vagina that is not normal, even if it’s a few spots between periods or after menopause
• blood in your poo or wee
• unexplained pain in the body that does not get better

What happens if you have cancer?#

Cancer won’t go away without treatment. The treatment depends on the type and stage of the cancer (how much it has grown and spread). The most common cancer treatments are:

• chemotherapy
• radiation therapy
• surgery
• immunotherapy

Your doctor will explain the options available to you. Each person is different, and some people have more than one type of treatment. If the cancer is found early, it may be easier to treat. If the cancer can’t be cured, your doctor may give you treatment to make you feel better by controlling your symptoms, so you might feel less pain and have a better quality of life.

Side effects of cancer treatments#

All cancer treatments can have side effects. Your treatment team will discuss these with you before you start treatment. Talk to your doctor or nurse about any side effects you are experiencing. Some side effects can be upsetting and difficult, but there is help if you need it.

Living with advanced cancer#

Advanced cancer usually means cancer that is unlikely to be cured. Some people can live for many months or years with advanced cancer, and palliative care can help during this time.

Most people continue to have treatment for advanced cancer as part of palliative care, as it helps manage the cancer and improve their day-to-day lives. Many people think palliative care is only for people who are dying, but it is for any stage of advanced cancer. There are doctors, nurses and other people who specialise in palliative care.

Treatment may include chemotherapy, radiation therapy or another type of treatment. It can help to:

• slow down how fast the cancer is growing
• shrink the cancer
• help you live more comfortably by managing symptoms, such as pain

Treatment depends on where the cancer started, how far it has spread, your general health, and your preferences and what you want to do. Ask your doctor about treatment and palliative care services that may help you.

Support for carers, family and friends#

Caring for someone with cancer can be difficult at times. If you are caring for someone with cancer, support is available — speak to your doctor or an experienced cancer nurse about services and resources that can help you and the person you care for.

Key points#

• Cancer is a disease of the cells, and it can start anywhere in the body.
• Benign tumours are not cancer and do not spread, while malignant tumours are cancer and can spread to other parts of the body.
• Cancer is not contagious — you cannot catch it from someone who has it.
• Finding cancer early, including through screening, makes it easier to treat, so see your doctor if you notice changes that are not normal for you.
• Treatment depends on the type and stage of cancer, and palliative care can help at any stage of advanced cancer.

Where to get help and trusted information#

For evidence-based global health guidance, see Source: World Health Organization (WHO).