NHS screening programme

What is screening?

A screening test is a check done on a healthy person to pick up a condition either before it develops or at a very early stage. If the screening test is positive, further tests may be needed. If these further tests confirm the result, treatment may be needed.

• For example, there is a long pre-cancer stage in most women who develop cancer of the cervix. At this stage, there are abnormal cells which could turn into cancer if not treated and there is a treatment which can destroy these abnormal cells and therefore stop them developing into cancer. So, if detected by the cervical screening programme, the woman can be treated and will never develop cancer of the cervix.

• Other conditions can be detected whilst they are still in the early stages and therefore easier to treat, before complications develop. One example is the bowel screening programme. Bowel cancers tend to cause very small amounts of bleeding as soon as they start developing. When the bowel cancer first starts to grow it does not usually cause any other symptoms and the blood loss is too small to see with the naked eye. The bowel screening programme looks for blood within the stool. If more than 100 micrograms of blood are found per milligram of stool then further tests are done to see if there is an early bowel cancer present. If this is found it can be removed, hopefully before it has a chance to spread or cause other problems.

Different types of screening tests are offered, depending on the condition they are screening for. For example,

• Aortic aneurysm. The screening test for an aortic aneurysm (a bulge in the aorta which is the big artery coming from the heart) is an ultrasound scan.

• Breast cancer. The screening test for breast cancer is a specific X-ray called a mammogram.

• Cancer of the cervix. The screening test for cervical cancer is a cervical smear.

Some screening tests are blood tests. Some screening tests involve a physical examination. Each screening programme has its own website (see the links in the last section below) which explains which test is done and what this involves.

What conditions are suitable for screening?

A large number of criteria must apply before a national screening programme is considered. For example:

• There must be a test available which picks up a disease or condition before symptoms develop.

• This test must be reasonably accurate. It should not be positive for too many people who do NOT have the condition and it must not miss many people who DO have the condition.

• The test must be reasonably simple to perform and acceptable to the people having the test.

• The benefits of the screening test must be greater than any potential harm or risks it could cause.

• The cost of the test, across the whole population, must not be more than the benefits it gives.

• There must be a treatment at the early stage of the condition or disease which will make a difference to the outcome. There is no point in screening for something if it cannot be successfully treated.

• The condition being screened for must have a significant impact on health and well-being.

• There must be an organised, efficient plan for what happens if the test is positive.

These are just some of the things which have to apply before a screening programme is rolled out across a country. In many conditions there is not a precise enough test, or there is not enough evidence that early treatment makes a difference.

For example, there is not yet a national screening programme for prostate cancer. There is a blood test, called the Prostate Specific Antigen (PSA) test. However, experts advising the national screening committee do not feel it is accurate enough yet to be rolled out into a national screening programme. Many men who do not have prostate cancer would have a positive screen and therefore have to have further investigations, which may themselves cause harm. Also, not all early prostate cancer progresses into a more aggressive form of cancer which causes illness and death. Therefore a significant number of men might go through unnecessary treatment for something which was never going to harm them and where the treatment itself can cause harm.

Not all experts agree but currently it is thought that screening all men would cause more harm than benefit. Therefore, this test is only used where doctors feel it would be helpful, or for men who choose to have it having understood the pros and cons. It is not a national screening programme. However a UK study is taking place to assess whether a successful prostate cancer screening programme can be created.

What are the benefits of screening?

Screening tests which have become part of the UK screening programme are believed to have great benefits.

• Prevention. In picking up problems early, many lives are saved and many health problems prevented. It is thought, for example, that 4,500 lives are saved every year in the UK by cervical screening.

• Early stages of cancer. For cancers, such as bowel cancer, which are picked up in the early stages, treatment is more likely to be successful. Operations involved are less extensive in the early stages of a cancer than in later stages. There is less chance of the cancer spreading if it has been detected early.

• Newborn babies screening. A number of screening programmes exist for newborn babies. These pick up uncommon abnormalities which may be corrected if picked up early enough. One example is the heel-prick test which takes a sample of blood to look for conditions such as congenital hypothyroidism or cystic fibrosis. If these are picked up and treated early, the longer-term effects are reduced significantly. Another example is that newborn babies have a thorough screening examination after birth, which is repeated at six-eight weeks. This is to look for particular problems with their eyes, heart, testicles and hips. This can prevent health issues later on in life, such as loss of vision and infertility.

• Pregnant women screening. There are several screening programmes which involve tests for pregnant women. One such test is a scan to look for abnormalities in the baby's development. This is an optional test and women may choose not to have testing. Some women will choose not to continue with their pregnancy if significant abnormalities are found in the baby's development.

To see the benefits of each individual screening programme, see the links below where the tests are listed.

What are the problems with screening?

All the advantages of screening tests have to be weighed against the possible problems or harm which they might cause. Issues to consider include:

• No guarantee. No test can be absolutely guaranteed to be accurate. So some people may be falsely reassured; others may think they have a problem when they don't.

• Unnecessary treatment. Some people may have treatment which wasn't actually needed as a result of a positive test.

• Worries. Tests can cause a lot of worry. This is particularly the case if a screening test comes up positive but further investigations are normal.

• Cost. Screening large numbers of healthy people is expensive and this uses funds which could otherwise be used to treat ill people. (Where the balance is right, this cost will be balanced by preventing health issues which are expensive to treat in future.)

• Negative results are not a guarantee for future protection. For some conditions screened, a negative result at one point in time does not rule out developing the condition in the future. The test cannot guarantee any protection for the years to come.

As discussed above, many illnesses do not have a test which fits all the conditions needed to use in a screening programme. There are some conditions where it would be an advantage to pick them up early but for which there are no suitable tests.

Even in well-established screening tests, such as breast screening, experts differ in their opinion about whether the benefits are worth the harms.

What screening programmes exist in the UK?

Screening programmes vary slightly between countries in the UK but, where the screening test is offered, it is the same in each country.

Currently the following screening programmes are running in the UK:

England

• Abdominal Aortic Aneurysm Screening Programme for men the year they turn 65.

• Bowel Cancer Screening Programme every 2 years for people between the ages of 54 and 74 (shortly to become aged 50 to 74); people can choose to continue past the age of 74 by requesting the test every 2 years.

• Breast Screening Programme every 3 years for women between the ages of 50 and 70; women can choose to continue past the age of 70 by requesting the test every 3 years.

• Cervical Screening Programme every 3 years for women between the ages of 24.5 and 50 and then every 5 years for women between the ages of 51 and 64.

• Diabetic Eye Screening Programme every year for people with diabetes.

• Fetal Anomaly Screening Programme offered in the first trimester of pregnancy to all pregnant women.

• Infectious Diseases in Pregnancy Screening Programme to all pregnant women.

• Newborn and Infant Physical Examination Screening Programme to all newborn babies.

• Newborn Blood Spot Screening Programme to all newborn babies.

• Newborn Hearing Screening Programme to all newborn babies.

• Sickle Cell and Thalassaemia Screening Programme to all pregnant women.

Northern Ireland

• Abdominal Aortic Aneurysm Screening.

• Breast Screening.

• Bowel Cancer Screening.

• Cervical Cancer Screening.

• Diabetic Eye Screening Programme.

• Antenatal Screening.

• Newborn Screening, which includes:

  • Newborn Hearing Screening.

  • Newborn Bloodspot Screening.

• Farm Families Health Checks Programme.
  

Scotland

• Abdominal Aortic Aneurysm (AAA) Screening.

• Bowel Screening.

• Breast Screening.

• Cervical Screening.

• Diabetic Retinopathy Screening (DRS).

• Pregnancy Screening and Newborn Screening, which include:

  • Blood Tests.

  • Screening for Sickle Cell and Thalassaemia Disorders.

  • Mid Pregnancy Scans.

  • Newborn Blood Spot Test.

  • Newborn Physical Examination Screening.

  • Newborn Hearing Test.

Wales

• Wales Abdominal Aortic Aneurysm Screening Programme.

• Bowel Screening Wales.

• Breast Screening Wales.

• Cervical Screening Wales.

• Diabetic Eye Screening Wales.

• Antenatal Screening Wales, which includes:

  • Fetal Anomaly.

  • Infectious Diseases in Pregnancy.

  • Sickle Cell and Thalassaemia.

• Newborn Bloodspot.

• Newborn Hearing Screening Wales.