Cancer - an overview

About cancer

Your body is made up of many different types of cells that form your tissues and organs. These cells normally divide and reproduce in a controlled way. This is how your body grows and repairs itself. However, cancer cells don't stop dividing and reproducing. They carry on growing in an uncontrolled way to form a lump called a tumour.

There are two main types of tumour – benign and malignant.

Benign tumours aren’t cancerous. They don’t spread to other parts of your body and don’t invade surrounding tissues. Benign tumours usually grow slowly. As a benign tumour gets bigger, it may start pressing on the organs and tissues surrounding it.

Malignant tumours are cancerous. They can spread to other parts of your body and invade surrounding tissues. This can cause tumours to develop in other areas of your body, called secondary tumours. Metastasis describes the spread of a cancer through the body. Malignant tumours usually grow faster than benign tumours.

Animation - how cancer develops


Types of cancer

There are more than 200 different types of cancer. They are named after the types of cells that they develop from and are grouped into the categories below.


This type of cancer starts off in epithelial cells. These are cells that line your organs and tissues. Lung cancer, prostate cancer, breast cancer and stomach cancer are all carcinomas.

The different types of carcinoma are named after the type of epithelial cell that they develop from. There are four main types of epithelial cells, so there are four main types of carcinoma.

  • Squamous cell carcinomas affect the flat cells that line your skin, mouth, airways and oesophagus (the pipe that goes from your mouth to your stomach).
  • Adenomatous cell carcinomas affect the glandular cells that line organs containing glands, including your stomach, bowel, pancreas and kidneys.
  • Transitional cell carcinomas affect the cells in your bladder and urinary tract.
  • Basal cell carcinomas affect the cells in one of the layers of your skin.

Carcinomas are the most common type of cancer; up to 85 in 100 diagnosed cancers are carcinomas. 


This type of cancer develops from the cells of your connective tissues, including bone, muscle, blood vessels and fat. The two main types are bone sarcomas and soft tissue sarcomas. Sarcomas are rare; they account for fewer than one in 100 diagnosed cancers.

Leukaemia and lymphoma

These are cancers of your blood and lymphatic system (the tissues and organs, including the bone marrow, spleen, thymus and lymph nodes, that produce and store cells that fight infection and disease). Only about seven in 100 people diagnosed with cancer have leukaemia or lymphoma. Some types of leukaemia are more common in children than adults.

Symptoms of cancer

The symptoms of cancer can vary widely depending on the specific type you have. There are, however, certain symptoms to look out for, including: 

  • a new lump in any area of your body, for example a breast lump if you're a woman or a testicular lump if you're a man
  • any unusual bleeding, for example blood in your urine, vomit or faeces
  • coughing up blood
  • a sore that won’t heal
  • unexplained weight loss
  • unexplained pain
  • feeling tired all the time
  • changes to a mole

These symptoms aren’t always caused by cancer but if you have any of them, see your GP.

Causes of cancer

Most cancers are thought to be caused by a combination of risk factors, including the following.

  • Increasing age. About two in three newly diagnosed cancers occur in people aged 65 or over.
  • Smoking. This is a major cause of lung cancer and can contribute to causing bladder, throat and several other cancers.
  • Genes. You may be more likely to get some types of cancer if family members have had them.
  • Diet. Eating a diet high in animal fats, red and processed meat, but low in fruit and vegetables, can increase your risk of getting certain types of cancer. Drinking excessive amounts of alcohol and being overweight can also increase your risk.
  • Ultraviolet (UV) rays. Prolonged exposure to the sun is known to cause skin cancer, including melanoma.
  • Infection. For example, a virus called human papilloma virus (HPV) can increase your risk of getting cervical cancer.
  • Exposure to certain substances that are known to cause cancer (carcinogens). These include asbestos and radioactive materials.
  • A weakened immune system. For example, if you have HIV/AIDS or are taking medicines that suppress your immune system.

Cancer isn't infectious and can't be caught from other people.

Diagnosis of cancer

Your GP will ask about your symptoms and examine you. He or she may also ask about your medical history.

Tests that are used to diagnose cancer include blood tests, X-rays and scans including MRI, CT and ultrasound.

You may need other tests depending on your symptoms and the area of your body that is affected. For example, your GP may arrange for you to have an examination using an endoscope to look into your stomach or bowel.

You will usually need to have a biopsy taken. A biopsy is a small sample of tissue. This will be sent to a laboratory for testing to determine the type of cells and if these are benign (not cancerous) or cancerous.

Doctors and surgeons stage and grade cancer to describe the size of the tumour and how far and fast it's growing. This is important because it can help determine what the best course of treatment will be.

Treatment of cancer

Your treatment will depend on the specific type of cancer you have and its stage and grade. Treatment may be given to: 

  • cure the cancer
  • shrink or slow down the cancer growth to prolong your life
  • reduce the symptoms caused by the cancer (palliative therapy)

The most common treatments for cancer often include having surgery to remove the tumour, but chemotherapy and radiotherapy may also be used. Other treatments include hormone therapy, biological therapies (which can be tablets or injections that target cancer cells), and bone marrow (stem cell) transplants. You may need to have more than one type of treatment. A specialist will discuss these treatments with you and go through the choices you may have. He or she may also ask whether you would like to take part in a clinical trial.

Help and support

Being diagnosed with cancer can be distressing for you and your family. Dealing with the emotional aspects, as well as the physical symptoms, is an important part of your treatment. Doctors and nurses who specialise in treating cancer can provide the support you need, and may be able to visit you at home. If you have an advanced type of cancer and treatment is going to be ineffective, palliative care is available to you in hospices or at home to help with your symptoms.

What are the most common types of cancer in the UK?


The most commonly diagnosed cancer in the UK is breast cancer, followed by lung, bowel and prostate cancer. Over half of all people who are newly diagnosed with cancer have one of these types.


Breast cancer is the most common type of cancer in the UK, even though it’s rare in men. In 2008, over 47,000 people were diagnosed with the disease. Breast cancer is very strongly related to age – nearly half of people diagnosed are between 50 and 69 years.

Lung cancer is the second most common cancer in the UK and almost 41,000 people were diagnosed in 2008. Smoking causes nine out of 10 deaths from lung cancer, which is why it’s very important to try to give up if you smoke, whatever your age.

About 40,000 people were diagnosed with bowel cancer in 2008, making it the third most common type in the UK. Like breast cancer, bowel cancer is very strongly related to age. More than eight in 10 people who are diagnosed are 60 years or older.

The fourth most common type of cancer in the UK is prostate cancer – just over 37,000 people were diagnosed in 2008. It’s the most common type of cancer in men and over half of those diagnosed are aged over 70.

How do I support my friend who has cancer?


It can be very upsetting if someone you know has been diagnosed with cancer, but there are lots of things you can do to help.


If a friend has cancer, it can be a very difficult time for both of you. It's important that you spend time with your friend so he or she doesn't feel alone. Talking to your friend will help you to understand better how he or she is feeling and coping with the illness.

You may find it hard talking to your friend at first as he or she may act as if everything is normal. If your friend doesn't feel ready to talk, let him or her know that you will be supportive and continue to be a friend. Look for information about the type of cancer your friend has to help you understand what he or she is going through.

Try to think about practical ways you can help. There are many things you could do, including cooking or picking up shopping. Remember, you can’t catch cancer, so don’t be afraid of seeing your friend. You could also offer to accompany him or her to doctors’ appointments or treatment sessions.

It's important that you remember to take time out for yourself as supporting somebody with cancer can be stressful. Talk to other people about how you're feeling – you may also find it useful to talk to your GP.

Can cancer be cured?


Many people can be cured of cancer, but it depends on a number of things including the type of cancer you have, the stage it’s diagnosed at and how well you respond to treatment. For most people, the earlier the cancer is diagnosed, the better.


There are over 200 different types of cancer and some are easier to cure than others. If cancer is diagnosed at an early stage, there is a better chance of it being cured because the tumour may be small and won’t have spread to other parts of your body.

If you have been diagnosed with cancer, ask your doctor what kind of treatment you will have and what the chances of the cancer being cured are. If your cancer can’t be cured, there are some treatments available that can be used to shrink the tumour or slow down its growth. They may be able to help reduce your symptoms and prolong your life.

There is a large amount of research going on into developing new cancer treatments. Researchers are developing new medicines all the time and you may be asked to take part in clinical trials to test these. Ask your doctor for more information. 

Can vitamin D protect against cancer?


Getting enough vitamin D may reduce your risk of developing a number of cancers, although more research needs to be done to be certain. Vitamin D is also well known to be important for bone health.


There is increasing evidence that vitamin D may help to reduce your risk of bowel cancer, and possibly also breast cancer but more research needs to be done to be certain.

Vitamin D is produced naturally by your body when your skin is exposed to sunlight and can also be obtained from some foods, such as oily fish. You may get enough vitamin D during summer by spending frequent short spells in the sun without wearing sunscreen (the exact time you need is different for everyone, but is typically only a few minutes in the middle of the day). However, do not let your skin redden. If you don't get much sun exposure and particularly during winter months, taking up to 25 micrograms of vitamin D a day (two high-strength 12.5 microgram capsules) can help to make sure you get enough.

Always read the patient information leaflet that comes with your supplements and if you are pregnant or breastfeeding, ask your pharmacist or GP for advice first. Talk to your GP before taking vitamin D supplements if you are taking diuretics for high blood pressure or have a history of kidney stones or kidney failure.