What is cancer ?

Cancer is a disease of the body’s cells. You get cancer when normal body cells get out of control, multiply and spread.

What are cells?

The body has billions of cells. They are so small that you can see them only with a microscope. They are a bit like building blocks – groups of cells make up all the organs and tissues of the body. The lungs, liver, kidneys and skin, for instance, are all made from cells. Our bodies automatically make new cells when we need them. If you cut your hand with a knife, your body makes cells to heal the wound and grow new skin. Children make new cells so they can grow into adults. Every day, some of our cells get old and die just through normal wear and tear, so we make new ones to replace them. Usually, cells grow in a controlled and orderly way. Each cell knows exactly what to do, when to do it… and when to stop. It has a nucleus (centre) that contains all the instructions it needs. But cancer cells are different... They don’t behave themselves! They have gone wrong in some way, and follow different instructions. They can avoid the body's attempts to control them.

  1. One difference between normal cells and cancer cells is that cancer cells don’t stop growing. They carry on multiplying and usually form a lump called a malignant or cancerous tumour. Sometimes, non-cancer cells carry on growing too, so not all tumours are cancers. If a tumour is not cancer, it is called a benign tumour. Benign tumours can cause problems, but they are not normally as dangerous as cancer.
  2. Cancer cells spread to nearby areas. This is called local spread. The cells take up more and more space and can push their way into healthy parts of the body and damage them.
  3. Cancer cells can also spread to distant parts of the body. They normally do this by getting into the bloodstream or the lymphatic system. Blood or lymph moves the cancer cells around the body until they get stuck somewhere. Then they start growing in this new place, forming secondary tumours or metastases.Most cancers form tumours – but not all do. Leukaemias, for instance, are blood cancers. In these diseases the cancer cells start to replace normal white cells. If we have too few white cells, we can’t fight infections and we can get very ill.Cancers can cause problems as they grow and spread. They may press on nerves and cause pain. They may cause fluid to build up – for example in the lungs, making it harder to breathe. They may cause a blockage – in the bowel, for instance. They may stop healthy parts of the body from working.Normally if we are infected by something – such as a flu virus – our bodies try to ‘fight it off’. We may not need to go to the doctor. But because cancer cells are quite like normal cells, our bodies don’t fight them in the same way. Left untreated, most cancers are very dangerous

Cancer and cell types:-

Most people are familiar with cancer types being described according to where the cancer first started in the body (the primary site), for example, lung cancer or breast cancer. The most common sites in which cancer develops include the:

  1. Skinskin
  2. Lungs
  3. Breasts
  4. Prostate
  5. Colon and rectum (large bowel).

Are there different types of cancer?

Yes. There are more than 200 types of cancer. Each grows and spreads in its own way, and causes its own set of symptoms. Each responds to treatment in its own way. Although there are lots of cancers, we can put almost all of them into these eight groups, depending on which body cells they start in...


cancers that start on the surface or lining of a body organ. The surface or lining may be on the inside of the body (eg lungs, bowel, bladder, stomach, uterus) or on the outside (eg skin). Around 9 out of 10 cancers are carcinomas.


cancers that start in the body’s bones, fat, muscles, tendons, cartilage or some other tissues. (These parts of the body are called connective tissue.)


cancers that start in the cells that make our skin colour.


cancers that start in cells called lymphocytes. These cells are in the bone marrow and lymph nodes, and they help us to fight infection.


cancers of the white blood cells. We need white cells to fight infection.


cancers of the plasma cells in bone marrow. These cells make antibodies that help us to fight infection.

Nerve cell tumours

cancers that start in the cells of the brain or spinal cord.

Germ cell tumours

cancers that start in the cells that make sperm (in men) and eggs (in women).Cancer can also be described according to the type of cell it started in. This can be just as important in how a cancer behaves and responds to treatment as the site where it started. You may come across words such as ‘adenocarcinoma’ or ‘squamous cell carcinoma’ when reading about cancer. These are the names given to cancers to describe the type of cell the cancer started in. Cells in our body is made up of millions of cells. The cells, organised together, make up all of our tissues and organs. There are different types of cells to carry out different functions in the body. Some types are very common and are found in almost all the organs in our body. Other types, such as the brain cells, are very specialised and only found in one part of our body.

The main types of cells in our body are:

Epithelial cells these cover the outside of our body (as skin) and make up tissues that line the inside of our bodies and cover our organs.Cells of the blood and lymphatic system these are found in our blood, in the bone marrow (where blood cells are made) and in the lymphatic system (which fights infection). Connective tissue cells these cells are found in supportive and connective tissues in our body such as the muscles, bones and fatty tissue. Cancers that start in each of these types of cells have different names.


Cancers that start in epithelial cells are called carcinomas. They are the most common type of cancer in adults and make up 80-90 out of every 100 cancers (80-90%). Most lung, breast, prostate and bowel cancers are carcinomas.

There are different types of epithelial cells:

Squamous cells are found in the skin and cover the surface of many parts of the body including the mouth, gullet (oesophagus) and the airways. Adeno cells form the lining of all the glands in the body including those in the breast, bowel, stomach, ovaries and prostate. Urothelial (transitional) cells line the bladder and parts of the urinary system.Basal cells are found in the skin. Carcinomas may start in any of these types of cells.

Leukaemias and lymphomas

Cancers that start in the blood or bone marrow (the tissues where white blood cells are formed to fight infection in the body) are called leukaemias. Cancers that start in the lymphatic system (which helps the body fight infection) are called lymphomas. Leukaemias and lymphomas are quite rare, making up fewer than 7 in 100 (7%) of cancers.


Cancers that start in connective tissue cells are called sarcomas. Sarcomas are rare. They make up fewer than 1 in 100 (1%) of cancers.

Sarcomas are split into two main types:

bone sarcomas, which are found in the bones soft tissue sarcomas, which develop in the other supportive tissues of the body. Cancers that start in other types of cells Cancer can develop in other types of cells but these cancers are rare. Brain cancers are the most common cancers in this group. Knowing how your body normally looks and feels can help you spot early any changes that could be caused by a cancer. Having any of the following symptoms doesn’t necessarily mean you have cancer, but it’s sensible to get them checked out by your GP. A lump anywhere on your body. Changes on your skin or to an existing mole (such as itching, bleeding, or a change in shape or colour). A cough or hoarseness that lasts for more than three weeks. A change in bowel habit that lasts for more than six weeks. Any abnormal bleeding from your vagina or back passage, in your urine or when being sick (vomiting). Unexplained, significant weight loss (5kg/10Ibs over a couple of months). Coughing up blood. Your doctor will want to know if you have any of these symptoms. Some people worry about what the doctor will say. It’s natural to be concerned about changes to your body and what they may mean. But the sooner you see your doctor, the sooner they can arrange any tests and explain what’s going on. Usually, the sooner a cancer is found the more successfully it can be treated. Some cancers have very specific symptoms, but not all cancers will have symptoms in the early stages. Some cancers are diagnosed by accident, while someone is being investigated or treated for another condition. Cancer can’t be diagnosed based on symptoms alone. Investigations, such as x-rays, scans and biopsies, are nearly always needed to make a diagnosis.

General signs and symptoms

The following are the most common signs and symptoms of cancer. If you have a symptom that isn’t listed here and that’s lasted for a few weeks, it’s a good idea to discuss it with your GP.


You should see your GP if you notice a lump or swelling anywhere on your body. It can be useful to tell your GP how long it’s been there and if it’s getting bigger or causes discomfort. It can be difficult to tell what a lump is just by feeling it. But if your GP suspects that you might have a cancer, they will refer you to an appropriate specialist for further tests.

Coughing and breathlessness

If you have a cough or feel breathless for more than three weeks, you should see your GP. Tell them if you have any blood in your sputum (phlegm) when you cough.

Change in bowel habit

Blood in your stools (bowel motions) can be a symptom of bowel cancer. The blood is usually dark but can be bright red in colour. You may notice a change in your normal bowel pattern, such as diarrhoea or constipation, for no obvious reason. Some people may have alternating episodes of diarrhoea and constipation. You may have a feeling of not having emptied your bowel properly after a bowel motion. Some people have pain in the tummy (abdomen) or back passage. If any changes in bowel habit last for more than six weeks, you should check them out with your GP.

Abnormal bleeding

Unexplained bleeding should always be checked out by your GP. Any unexplained bleeding is a sign that something might be wrong and should always be checked out by your GP. Bleeding between periods or after sex may be caused by cancer of the womb or cervix. Women who have any vaginal bleeding after they have had their menopause should always see their GP. Blood in your urine may be caused by bladder or kidney cancer. Coughing up blood in your sputum (phlegm) can sometimes be a sign of lung cancer. Vomiting blood can be a sign of stomach cancer, although it can also be due to a stomach ulcer. Bruising and nosebleeds are rarely signs of cancer, but can in some cases be caused by leukaemia. However, people with leukaemia usually have other symptoms too. Unexplained weight loss 10 If you’ve lost a lot of weight over a short period of time (a couple of months or less) that can’t be explained by changes in your diet, increased exercise or stress, it’s important to tell your GP. Suspicious moles or skin changes Malignant melanoma is a type of skin cancer that often starts with a change in the appearance of normal skin. This can look like an abnormal new mole. Fewer than one third of melanomas develop in existing moles. Any of the following changes should always be checked out. Asymmetry - Melanomas are likely to be irregular or asymmetrical. Ordinary moles are usually symmetrical (both halves look the same). Border - Melanomas are more likely to have an irregular border with jagged edges. Ordinary moles usually have a well-defined, regular border. Colour - Moles tend to be one shade of brown. Melanomas often have more than one colour. Diameter (width) - Melanomas are usually more than 7mm in diameter. Moles are normally no bigger than the blunt end of a pencil (about 6mm across). Evolving (changing) - Look for changes in the size, shape or colour of a mole. It’s important to see your GP if you have any unusual marks on the skin that last for more than a few weeks, or if you have a mole that shows any of the above signs.


A hoarse voice may be a sign of cancer of the larynx. Hoarseness can occasionally be a symptom of other cancers, such as thyroid cancer, cancer of the gullet (oesophagus) or lung cancer. If hoarseness continues for longer than two weeks, you should tell your GP.


People often think that pain is a symptom of cancer, but many people with cancer have no pain in the early stages. Some people with cancer will never have pain.

The most common cancers in men and women :-

There are more than 200 types of cancer. Some are very common and others are very rare. In the UK, the four most common cancers in men are:
1) Prostate cancer
2) Lung cancer
3) Large bowel cancer
4) Bladder cancer.

The four most common cancers in women in the UK are:

1) Breast cancer
2) Large bowel cancer
3) Lung cancer
4) Ovarian cancer.

Lung cancer symptoms

Lung cancer is common in both men and women. Smoking cigarettes is known to be the cause of most lung cancers. The symptoms of lung cancer may include any of the following: continued coughing for three weeks or longer, or a change in a long-standing cough a chest infection that doesn’t get better increasing breathlessness and wheezing coughing up blood in your sputum (phlegm) a hoarse voice a dull ache or a sharp pain when you cough or take a deep breath loss of appetite or loss of weight difficulty swallowing excessive tiredness (fatigue) and lethargy. It’s important to have any of these symptoms checked by your GP as early as possible.

Large bowel cancer symptoms

The large bowel is made up of the colon and the rectum, and is part of the digestive system. Most cancers of the large bowel develop in the colon. The following can all be symptoms of large bowel cancer: dark or bright red blood in or on your stools a change in your normal bowel habit, such as diarrhoea or constipation, for no obvious reason that lasts for longer than six weeks unexplained weight loss pain in the tummy (abdomen) or back passage a feeling of not having emptied your bowel properly after a bowel motion 12 general discomfort, such as gas, bloating or cramps, in the tummy (abdomen). Sometimes tiredness (fatigue) is a symptom of a bowel cancer. This can happen if the cancer has been bleeding, which means that the number of red blood cells in your body is reduced (anaemia). Anaemia may also make you feel breathless. Sometimes a cancer can cause a blockage (obstruction) in the bowel. The symptoms of this are being sick (vomiting), constipation, pain in the abdomen or a bloated feeling. Although these symptoms can be caused by conditions other than large bowel cancer, it’s important to get them checked by your doctor.

Prostate cancer symptoms

The prostate is a small gland found only in men. It‘s about the size of a walnut and surrounds the first part of the tube (urethra) that carries urine from the bladder to the penis. Many men with early prostate cancer are unlikely to have any symptoms, as these only occur when the cancer is large enough to put pressure on the urethra. In men over the age of 50, the prostate gland often gets larger due to a noncancerous condition known as benign prostatic hyperplasia or benign prostatic hypertrophy (BPH). The symptoms of both benign enlargement of the prostate gland and a malignant tumour (cancer) are similar and can include any of the following: difficulty in starting to pass urine a poor or weak flow of urine urgently needing to pass water passing urine more frequently than usual, especially at night blood in the urine, although this is uncommon. If you have any of these symptoms, you should discuss them with your GP.

Bladder cancer symptoms

The bladder is a hollow, muscular, balloon-like organ that collects and stores urine. The most common symptoms of bladder cancer are: Blood in the urine - This usually happens suddenly and may come and go. It’s not usually painful. Sometimes the blood in your urine can’t be seen and is picked up by a urine test. Bladder changes - You may have a burning feeling when you pass urine, or need to pass urine more often or urgently than usual. These are all symptoms of bladder irritation and 13 are more likely to be due to an infection than cancer. Your GP may want to investigate further if you have repeated infections. If you have any worrying symptoms, getting them checked out with your GP is the best way to find out the cause.

Breast cancer symptoms

Breast cancer mainly affects women, but in rare cases can affect men too. In most cases, the first symptom of breast cancer is a painless lump. You should visit your doctor straight away if you notice a lump or other changes in your breast(s). Although most breast lumps are not cancerous (benign), they still need to be checked carefully to rule out the possibility of cancer. Other, less common signs of breast cancer may include: a change in the size or shape of a breast dimpling of the skin on the breast a thickening in the breast tissue a nipple becoming inverted (turned in) a lump or thickening behind the nipple a rash (like eczema) affecting the nipple a swelling or lump in the armpit blood in discharge from the nipple. Pain in the breast is not usually a symptom of breast cancer, but it can occur.

Ovarian cancer symptoms

Symptoms of ovarian cancer can be quite vague and may not occur until the cancer is at a late stage. When symptoms occur, they can include any of the following: loss of appetite feeling sick (nausea) excessive gas (wind) a bloated, full feeling unexplained weight gain swelling in the abdomen – this may be due to a build up of fluid (ascites), which can also cause shortness of breath pain in the lower abdomen 14 changes in bowel or bladder habits, such as constipation, diarrhoea or needing to pass urine more often than usual lower back pain pain during sex abnormal vaginal bleeding. If you have any of the above symptoms, it’s important to have them checked by your doctor.


Screening is a way of testing healthy people, either to see if a cancer can be found early or to detect changes that may develop into cancer at a later date. There are national screening programmes for bowel, breast and cervical cancer that monitor people regularly. Speak to your GP for further details.

Who gets cancer?

Each year nearly 300,000 people are diagnosed with cancer in the UK. It has been estimated that more than 1 in 3 people (33%) will develop cancer at some point in their lifetime. Cancers can occur at any age, but the risk of developing cancer increases with age. Cancer isn’t common in children or young people. Three-quarters (75%) of all newly diagnosed cancers occur in people aged 60 or over. Less than 1 in 100 (1%) of cancers are diagnosed in children, aged 14 years or under. About 1 in 10 (10%) of cancers are diagnosed in people aged 25-49. Some cancers are very common and others are very rare. The most recent statistics for the UK (from 2008) show that for men the most common cancer is prostate cancer (24% of all cancers in men), followed by lung cancer (15%), colon and rectal cancer (14%) and bladder cancer (5%). For women, the statistics show that the most common cancers are breast cancer (31%), colon and rectal cancer (12%), lung cancer (12%) and womb cancer (5%). Nearly a third (31%) of all cancers diagnosed in children are leukaemia. Teenagers and young people (aged 15-24) are more likely to be diagnosed with Hodgkin lymphoma, testicular cancer, melanoma and leukaemia. The most common types of cancer diagnosed in adults aged 25-49 are breast cancer, melanoma, bowel and cervical 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, cutting down our alcohol intake and getting regular exercise. We’re getting better at recognising and treating cancer, 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.

How is cancer treated?

There are several different types of cancer treatment.

Some are used to treat cancer in a particular (local) area of the body. These are called local treatments. They include surgery and radiotherapy. Other treatments can treat cancer in more than one part of the body at a time. These are called systemic treatments. Chemotherapy, hormonal therapy and biological therapy generally work in this way.
The main types of treatment for cancer are described here. It’s quite common for a combination of treatments to be used.

Surgery :-

An operation to remove the tumour is the main treatment for many types of cancer. Surgery is most likely to be used if the cancer is only in one area of the body and has not spread. It can sometimes be used to remove a cancer that has spread to another area of the body, but this is less common.

Radiotherapy :-

Radiotherapy uses high energy x-rays to destroy cancer cells. The radiation is targeted at the area affected by cancer so that it does as little harm as possible to normal cells. One of the most common side effects is tiredness. Other side effects depend on the part of the body being treated.

Chemotherapy :-

Chemotherapy uses anti-cancer (cytotoxic) drugs to destroy cancer cells. There are more than 50 different chemotherapy drugs. Sometimes treatment is with just one chemotherapy drug but often two or more drugs are given together. This is known as combination chemotherapy. The type of chemotherapy treatment you are given depends on the type of cancer you have. Chemotherapy can cause various side effects depending on which drug (or combination of drugs) is used. However, there are many ways of preventing or reducing the side effects of chemotherapy.

Hormonal therapy :

Hormones are natural substances made by the body that control the growth and activity of certain cells. Some cancers depend on particular hormones in order to grow. Hormonal therapies reduce the levels of these hormones in the body or block the hormones from reaching cancer cells. This shrinks the cancer and stops it growing.

Biological therapy :-

Biological therapies work in various ways to destroy cancer cells. They can: stimulate the body’s defences (immune system) to attack the cancer attach to particular types of cells (including cancer cells) in the body so that they die. interfere with a cancer’s ability to grow.stop a tumour from making its own blood supply so it can’t get the oxygen and nutrients it needs. Some biological therapies will do just one of these things while others may use two or more of these methods to attack the cancer. Biological therapies can be given different names according to how they work. Some of the main types of biological therapies used to treat cancer are monoclonal antibodies, cancer growth inhibitors and angiogenesis inhibitors. Research is trying to discover whether other types of biological therapy such as vaccines and gene therapy can be used to treat cancer. This type of research is in the very early stages.

Why do cancers come back?

Sometimes cancer can come back. This can happen because tiny cancer cells, which can’t be seen with the naked eye or on scans, can be left behind after cancer treatment. Over time these cancer cells can begin to divide again and form a tumour. Treatment may be given to try to get rid of all the cancer so that it doesn’t come back. Many people may have an operation to remove the tumour. Often, to make sure all the cancer cells are taken away during the operation, some healthy tissue around the tumour will also be removed. To help reduce the risk of any cancer cells being left behind after surgery, other treatments such as chemotherapy, radiotherapy and biological therapy may also be used. For some types of cancer an operation isn’t an appropriate treatment. In this case chemotherapy, radiotherapy or biological therapy may be used. These treatments aim to destroy as many of the cancer cells as possible. Often a combination of treatments is given, which can be more effective. Unfortunately, no treatment is guaranteed to be 100% effective. Sometimes cancer cells can remain and in some people the cancer might come back - sometimes many years later. If cancer comes back in the same area of the body it’s known as a local recurrence. If cancer develops in a different part of the body, it’s called a metastasis or secondary cancer. A secondary cancer can develop if cancer cells break away from the original (primary) cancer and spread to other organs in the body through the bloodstream or lymphatic system. When these cells reach a new area of the body they grow to form a new tumour. If cancer does come back it can often be treated again. Usually in this situation, treatment is given to control the cancer, but it may be possible to give treatment that aims to get rid of the cancer.

Cancer statistics are often used to:

Statistics are based on trends in large numbers of people. They are often used to help explain what the chances (probability) are of something happening. But they can’t tell you for certain what will happen to a particular person. Statistics can sometimes help us to make decisions about which treatments to have. For example, if research shows that 3 out of every 4 people (75%) benefit from a particular cancer treatment, this means there’s a good chance it will be helpful to you, although this isn’t guaranteed. Because cancer statistics are usually quite general, while you and your situation are unique, there won’t be any statistics that can say exactly what will happen in your case. Your doctor can help you understand how any statistics that they do use relate to your treatment and situation. It’s not unusual for people to find statistics confusing and difficult to understand. If you don’t understand the statistics your doctor gives you, it’s fine to ask them or your nurse to explain them again, possibly in a differentway. You could also discuss them with one of our cancer support specialists.