Cancer is a term that is used to refer to a number of conditions where the body's cells begin to grow and reproduce in an uncontrollable way. This rapid growth of cancerous cells is known as a malignant tumour. These cells can then invade and destroy healthy tissue, including organs.
Cancer sometimes begins in one part of the body before spreading to other parts. This process is known as metastatis.
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How common is cancer?
Cancer is a common condition and is a serious health problem, both in the UK and across the world. It is estimated that 7.6 million people in the world died of cancer in 2007. In the UK, cancer is responsible for 126,000 deaths per year. One in four people die from cancer.
Types of cancer
There are hundreds of different types of cancer. The most common cancers in the UK are:
- Breast cancer.
- Prostate cancer.
- Lung cancer.
- Cancer of the colon, or rectum.
- Bladder cancer.
- Cancer of the uterus (womb).
Risk factors for cancer include smoking, drinking alcohol, obesity, poor diet, lack of exercise, and prolonged exposure to sunlight.
Treatments for cancer include surgery, chemotherapy and radiotherapy. Some cancers can be cured if detected early enough.
Making some simple changes to your lifestyle can significantly reduce your risk of developing cancer. Eating a healthy diet, taking regular exercise, and avoiding smoking will all help to lower your risk of getting major health conditions, such as cancer.
Symptoms of cancer
The symptoms of cancer vary depending on what part of your body is affected. However, cancer symptoms can be broadly grouped into three categories. These are:
- local symptoms - these occur when the cancer is contained in one part of your body,
- symptoms of metastasis - these are symptoms caused by the cancer beginning to spread to other parts of your body, and
- systemic symptoms - these are symptoms that are caused by the cancer having spread throughout your body.
Common local symptoms include:
- unusual swelling, or lumps,
- jaundice, and
Common metastasis symptoms include:
- swollen glands,
- coughing blood, and
- bone pain.
Common systemic symptoms include:
- weight loss,
- loss of appetite,
- tiredness, and
- night sweats.
Many of the above symptoms can be caused by conditions other than cancer. Therefore, if you have any of the above symptoms, you should not assume that you have cancer. Your GP will be able to advise you.
Causes of cancer
Cancer begins with an alteration to the structure of DNA that is found in all human cells. This is known as a genetic mutation. The DNA provides the cells with a basic set of instructions, such as when to grow and reproduce.
The mutation in the DNA changes these instructions, so that the cells carry on growing. This causes the cells to reproduce in an uncontrollable manner producing a lump of tissue, known as a tumour.
How does cancer spread?
Cancer is known to affect two specific genes known as the:
- oncogene, and
- tumour suppresser gene.
The oncogene is responsible for encouraging cell growth. Cancer seems to cause the oncogene to go into 'overdrive' so that the cells grow and multiply at a faster rate.
Cancer also deactivates the tumour suppresser gene. This gene is designed to regulate cell growth by making sure that cells only reproduce when needed.
The combination of the overactive onocgene, and the deactivated tumour suppressor gene means that the cancer can quickly grow and spread to the other parts of the body, usually via the lymphatic system.
The lymphatic system is a series of glands (or nodes) that are spread throughout your body, much like your blood circulation system. These glands produce many of the specialised cells needed by your immune system.
Once the cancer reaches the lymphatic system it is capable of spreading to any other part of your body, including your bones, blood, and organs.
What causes cancer?
Cancer can be caused by:
- carcinogens - chemicals that are known to cause the mutations associated with cancer, including alcohol and tobacco,
- exposure to a significant amount of radiation,
- infectious diseases such as the human papillomavirus (HPV),
- hormonal imbalance which can occur during the menopause, and
- conditions that affect the immune system, such as HIV.
Some types of cancer can run in families. For example, your risks of developing certain types of breast, or ovarian, cancer are higher if you have a close relative who developed the condition.
Diet and lifestyle are also important factors in the development of cancer. People who take regular exercise, eat a healthy, balanced diet, and are a healthy weight, have a lower risk of developing cancer. However, not taking exercise, eating a high fat diet, and being obese increases your chances of developing cancer.
Specific causes of cancer are discussed below.
It is known that exposure to certain chemicals can cause the mutations that lead to cancer. The most common carcinogen is tobacco smoke, which can cause lung and bladder cancer. Excessive alcohol consumption can also cause cancer, as can exposure to asbestos fibres.
Exposure to significant levels of radiation can cause cancer. This includes over-exposure to sunlight, or over-use of tanning beds, or lamps; all of which can cause skin cancer.
However, not all forms of radiation are dangerous. For example, the amount of radiation that is used by X-rays, or radiography machines, is small and will not cause you any harm.
Many viral infections can damage cells and cause cancer. The most common infectious conditions known to cause cancer are outlined below.
- Human Papilloma Virus (HPV), which is responsible for 95% of all cases of cervical cancer.
- hepatitis B and hepatitis C, both of which can cause liver cancer.
- Epstien-Barr virus, which is responsible for glandular fever, and has been linked to an increased risk of developing Hodgkin's lymphoma, which is a cancer of the lymphatic system.
- Human T-lymphotropic virus, which is blood-borne virus that is rare in the UK but common in other parts of the world, such as Japan and Africa and is known to cause leukaemia.
It is thought that changes in hormone levels can trigger cancerous cell growth in a similar way to exposure to carcinogens. This is why breast cancer is more common in post-menopausal women, as the menopause causes a change of the levels of the hormone, oestrogen, in the body.
Conditions that affect the immune system
Certain cancers, such as Karposi's sarcoma, and lymphoma, are common in people whose immune system is not functioning properly due to a medical condition, such as HIV.
There are a number of tests that can be used to detect the presence of cancer. These include:
- blood tests - some forms of cancers release proteins into the blood,
- a magnetic resonance (MRI) scan,
- a computerised tomography (CT) scan, and
- an endoscopy - where a flexible tube with a camera on the end is used to look inside your body.
If the presence of cancer is suspected, a diagnosis can normally be confirmed by carrying out a biopsy. This is a procedure that involves surgically removing a small piece of affected tissue and then testing it for the presence of cancerous cells.
Biopsies are very useful for diagnosing cancer, and they can often be used to determine whether the cancer has spread to other parts of the body, or the likelihood that it will spread.
Additional biopsies may also be carried out on the nearest lymph nodes to the site of the cancer in order to check that the cancer has not started spreading through the lymphatic system.
In treating cancer, the aim is to remove the cancerous cells while making sure that the cancer does not reoccur. This can be challenging because even if only one cancerous cell remains after treatment, it has the potential to cause a new tumour.
Different techniques are often used in combination as this can increase the chances of all the cancerous cells being removed. The main techniques are outlined below.
If the cancer is detected in its early stages, it may be possible to surgically remove the affected tissue. In some cases, it may be necessary to remove the entire organ, such as the prostate gland (prostatectomy), or breast (mastectomy).
Chemotherapy and radiotherapy may also be used before and after surgery to increase the chances of success.
Chemotherapy involves the use of powerful cancer-killing medicines. These medicines damage the DNA of the cancerous cells, interrupting their ability to reproduce.
A combination of different medicines is normally used. Chemotherapy is normally used in combination with radiotherapy and surgery.
The medicines that are used in chemotherapy can sometimes damage healthy tissue, as well as the cancerous tissue and, unfortunately, adverse side effects are common.
Side effects of chemotherapy can include:
- hair loss, and
However, the side effects should stop once the treatment has finished. Chemotherapy can also weaken your immune system, making you more vulnerable to infection.
For more information about chemotherapy, see the 'related articles' section.
Radiotherapy involves using pulses of radiation to damage cancerous cells. As with chemotherapy, the process also damages healthy cells but, unlike the cancerous cells, the healthy cells have the ability to repair themselves.
However, if you have radiotherapy, you may experience side effects while you are waiting for the healthy cells to repair themselves. These include:
- loss of appetite,
- hair loss,
- sore skin, and
- a lack of interest in sex.
The side effects of radiotherapy can persist for several weeks, or months, after treatment has finished. See the 'related articles' section for further information about radiotherapy.
The growths of some cancers, such as breast, or prostate cancer, can be slowed by blocking the effects of certain hormones, such as testosterone, or oestrogen.
However, blocking the effects of certain hormones can cause related side effects. In women, the possible side effects of blocking the hormone oestrogen may include:
- hot flushes and sweats,
- loss of interest in sex,
- nausea and vomiting,
- aching joints,
- headaches, and
- skin rashes.
In men, the possible side effects of blocking the hormone testosterone may include:
- hot flushes,
- weight gain,
- loss of interest in sex,
- an inability to obtain an erection, and
- swelling of the breasts.
Monoclonal antibody therapy
Monoclonal antibody therapy is a relatively new kind of treatment that was first introduced in the late 1990s. Monoclonal antibodies are antibodies that are genetically engineered in a laboratory. They are designed to directly target and attack cancer cells. This is why monoclonal antibody therapy is sometimes referred to as targeted therapy.
There are several ways that monoclonal antibodies can attack cancerous cells. They can:
- kill the cancerous cells by delivering tiny pellets of radioactive material to them,
- deliver a small amount of chemotherapy medicine directly into the cancerous cells, and
- block the signals in the cancerous cells that cause them to grow and reproduce.
Some types of monoclonal antibody therapy are still considered to be experimental, and will only be used when other treatments have failed. However, some forms of the therapy are now commonly used, such as the medicine Herceptin, which is sometimes used in the treatment of breast cancer.
The medicines that are used in monoclonal antibody therapy are administered directly into the vein (intravenously). Side effects of monoclonal antibody therapy may include:
- skin rashes,
- flu-like symptoms, such as chills, fever, and muscle aches,
- itchy skin, and
Monoclonal antibody therapy has been known to cause heart problems in some people, such as heart disease, or heart attack. Therefore, it is likely that you will not be able to receive monoclonal antibody therapy if you have a history of heart disease.
If you do have monoclonal antibody therapy, your heart function will be regularly monitored during your treatment. If monitoring reveals that your heart function is being adversely affected, treatment will have to be stopped.
Rarely, monoclonal antibody therapy can cause severe allergic reactions in some people. This is known as an infusion reaction and can be potentially fatal if left untreated.
Most infusion reactions happen within 24 hours of the first time somebody begins treatment, so it is likely that you will be closely monitored once your treatment begins. If you begin experiencing the symptoms of an infusion reaction, anti-allergy medicines, such as corticosteroids, can be used to relieve symptoms.
Immunotherapy is a form of monoclonal antibody therapy that uses the body's immune system to attack the cancerous cells.
Normally, the body does not regard the cancerous cells as a foreign object, so the immune system does not attack them.
However, in immunotherapy, the monoclonal antibodies change the composition of the cancerous cells in such a way that the immune system regards them as a foreign object. It then starts attacking the cells, in the same way that it would normally attack an infection.
The side effects of immunotherapy are the same as the other types of monoclonal antibody therapy (see above).
Angiogenesis inhibitor therapy
Another new type of cancer treatment is angiogenesis inhibitor therapy. In order to grow, tumours need to create new blood vessels - a process known as angiogenesis.
Angiogenesis inhibitors are medicines that block the creation of new blood vessels, slowing the growth of the tumour.
The medicines cannot kill tumours, but have been shown to be effective in treating some forms of cancer when used in combination with chemotherapy and radiotherapy.
Alternative and complementary therapies
A large number of alternative therapies have been suggested for the treatment of cancer, such as homeopathy, vitamin supplements, or special diets. However, there is no clinical evidence that these alternative therapies are effective.
Complementary therapies are designed to complement conventional treatment, but not replace it. A number of complementary therapies have been shown to be of some use in coping with the symptoms and psychological effects of cancer.
Examples of complementary therapies include:
- relaxation techniques, such as mediation,
- hypnotherapy, and
A reputable complementary therapist will never make claims that their therapy alone can cure cancer, or try and persuade you to abandon your conventional treatment. The British Complementary Medical Association provides contact details of complementary therapists who have met their professional and ethical standards. See the 'selected links' section for more details.
Much of the current research into cancer is focused on understanding more about the genetics of cancer. By finding out more about the specific genetic changes that occur when a cell becomes cancerous, it is then possible to develop new tests to detect cancer in its early stages.
An increased understanding in the genetics of cancer will also allow more effective types of monoclonal antibodies to be developed.
British researchers are also attempting to develop a new method of magnetic resonance imaging (MRI) which, if successful, promises to be 10,000 times more accurate than the current generation of MRI technology. This should allow tumours to be detected while they are in their early stages.
Another avenue of research is to identify people who are most at risk of developing certain types of cancer due to their genes. This will allow more efficient and effective screening programmes to be created, and it may be possible to then use medicines that prevent these types of cancer from occurring.
Complications of cancer
Being diagnosed with cancer, particularly if it is incurable, can be very distressing. For many, the news is difficult to take in and comprehend. Many people who are diagnosed with cancer experience the classic stages of the grieving process. These are outlined below.
- Denial - you may initially disbelieve the diagnosis and think that there is nothing wrong with you.
- Anger - you may lash out at friends, family, or medical staff.
- Bargaining - sometimes, people with terminal conditions will try to 'bargain' with their doctors, asking for any sort of treatment that can prolong their life.
- Depression - you may lose all interest in life and feel that your situation is hopeless.
- Acceptance - in time, most people will eventually accept the diagnosis.
If you have been diagnosed with cancer, talking to a counsellor, or psychiatrist, may help you combat feelings of depression and anxiety. Taking anti-depressants, or medicines that help reduce feelings of anxiety, may also help as you move through the grieving process. Your GP, or the doctor who is treating you, will be able to advise you about this.
It is estimated that up to half of all cancer cases could have been prevented. The information below provides advice about how to help prevent cancer.
Smoking cigarettes exposes your body to more than 4,000 chemicals, many of which are carcinogenic. Smoking is responsible for 90% of all cases of lung cancer, and one in three cancer deaths are caused by smoking.
Stopping smoking brings both short- and long-term health benefits. For example, if you manage to stop smoking for 10 years, your risk of developing lung cancer will be cut by 50%.
The NHS Smoking Helpline can offer you advice and encouragement to help you quit smoking. You can call on 0800 022 4 332, or visit the NHS Go Smokefree website. See the 'selected links' section for further details.
Your GP, or pharmacist, will also be able to provide you with help and advice about giving up smoking
Despite the stories that you read in the newspaper, there is no single food that will dramatically reduce, or increase, your risk of developing cancer. It is the overall content of your diet that is important, particularly your consumption of fruit and vegetables. In fact, many experts believe that after quitting smoking, eating regular portions of fruit and vegetables is the second best way to prevent cancer.
Fruit and vegetables contain special chemicals known as antioxidants, which are thought to help protect cells from becoming damaged.
You should aim to eat at least five portions of a variety of fruit and vegetables every day. Leafy vegetables, such as lettuce, spinach, and cabbage, are thought to provide the most protection against cancer. Your diet should also be low in fat, and high in starchy foods, such as wholemeal bread, cereals, and potatoes.
It is recommended that you limit your consumption of red and processed meat to no more than 90g (3oz). Examples of red and processed meat include beef, lamb, sausages, burgers, and pork.
Excessive salt consumption has also been linked to an increased risk of cancer, as well as heart disease, and stroke. Do not eat more than 6g (0.2oz) of salt a day. One teaspoon is approximately 6g of salt.
The uses of dietary supplements, such as beta-carotene, are not recommended because there is not enough evidence about either their effectiveness, or their long-term effects. Also, there is some evidence that beta-carotene may actually increase the chances of you developing some types of cancer.
You should be able to get all the vitamins and nutrients you need by eating a healthy, balanced diet.
Research has suggested that being overweight is a significant risk factor for developing certain types of cancer, such as breast, colon, and kidney cancer. The risk factor becomes even more significant if you are obese.
Weight is defined by using the body mass index (BMI). You can calculate your BMI by dividing your weight, in kilograms, by the square of your height, in meters.
If your BMI is above 25, you are classed as overweight, and if it is above 30, you are classed as obese. The higher your BMI is, the greater your risk of developing cancer, as well as other serious conditions, such as diabetes, heart disease, and stroke.
Ideally, your BMI should be between 18.5-25. A calorie controlled diet, combined with regular exercise, is the best way to safely lose weight. Your GP, or a dietician, will be able to provide you with advice about how you can change your diet in order to lose weight safely.
All scientific evidence shows that rates of cancer are a lot lower in people who take regular exercise. Regular exercise will also reduce the risk of other serious conditions, such as heart disease, and stroke.
For most people, thirty minutes of vigorous exercise a day, at least five times a week, is recommended. The exercise should be strenuous enough to leave your heart beating faster, and you should feel slightly out of breath afterwards. Examples of vigorous exercise include going for a brisk walk, or walking up a hill. However, if you have never exercised before, or if you have not exercised for some time, you should seek advice from your GP before starting a new programme of exercise.
Excessive consumption of alcohol has been linked to an increased risk of developing liver cancer. Therefore, limiting the amount of alcohol that you drink can help prevent damage to your liver, and lower your risk of liver cancer.
The recommended daily amount of alcohol consumption is between 3-4 units for men, and between 2-3 units for women. A unit of alcohol is equal to about half a pint of normal strength lager, a small glass of wine, or a pub measure (25ml) or spirits.
The NHS offers screening programmes for cervical cancer. Women between 25-49 years of age are invited for screening every three years, and women aged between 50-64 are invited every five years. It is important to make sure that your GP surgery has your up-to-date contact details so that you continue to get screening invitations.
If detected early enough, treatment for cervical cancer has an excellent success rate, which is why it is important that you attend all your scheduled screening appointments.
A similar programme is in place for breast cancer. Women who are between 50-70 years of age (the group who are most at risk from getting breast cancer) are recommended to attend screening appointments every three years.
For more information about cervical cancer and breast cancer, see the 'related articles' section.
A NHS screening programme for bowel cancer is being rolled out across England, and is already in place in many Primary Care Trusts (PCTs). It is hoped that full coverage will be achieved by the beginning of 2009.
The programme offers screening every two years to all men and women who are between 60-69 years of age. People who are over 70 years of age are able to request a screening appointment every two years, but do not receive an automatic invitation.
A national vaccination programme for the HPV virus - the leading cause of cervical cancer - will be introduced for girls who are between 12-13 years of age, as part of the national immunisation programme. There will also be a two year catch up programme, which is due to start in the autumn of 2009, which will include all girls who are up to 18 years of age (but not those who are 18).
You should always use a condom during sex in order to protect yourself against the HPV virus.
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NHS Choices links
- Carers Direct
- Carers: end of life issues
- Go smokefree
- Health A-Z: chemotherapy
- Health A-Z: radiotherapy
- Health A-Z: breast cancer
- Health A-Z: lung cancer
- Health A-Z: bowel cancer
- Live Well: cancer
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