Screening FAQ: what it is and what it isn’t
Screening aims to detect an illness in the early stages before symptoms start. This means that this is a much better chance of having a successful treatment.
Some of the screening tests we offer are for early cancer detection such as bowel, breast and cervical. Some screening tests are for other illnesses such as early detection of diseases that babies are born with through to diabetic eye screening to check the back of the eyes to prevent sight loss.
The GHA offers a range of screening tests similar, but not identical, to the NHS. The reason we do not offer the identical screening programs is because, we adapt ours to our local population needs and the healthcare services that we provide here.
For example, our breast screening program starts at a younger age because our experiences are that women living in the Mediterranean region can develop breast cancer from a younger age. This is why we offer screening from the age of 40 years old rather than 50 years old in England in the NHS.
The following FAQs help explain what screening is, what is not screening, why this is important and the limitations of screening tests.
You do not have to take up the offer of a screening test but we would encourage you to do so.
Each program can give you more specific details about the screening test and what is involved.
This is important because you are giving your informed consent to having the screening test.
This FAQ will help you make a decision as to whether to accept the invitation for screening, and this is especially important for the cancer screening programs. These being for breast, bowel and cervical cancer.
| 1. Why do you offer screening tests? | Screening aims to detect an illness in the early stages before symptoms develop. This means that there is a much better chance of having a successful treatment because of an earlier diagnosis.
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| 2. What do you mean when you use the term a screening program? | Many people use the term ‘screening’, when from a public health perspective there is a specific description of what is classified as screening defined by the internationally recognised Wilson and Junger criteria.
The reason that it is important that the correct terminology be used is because there are a number of criteria that have to be met for a service to be classified as a screening program. The impact is that if a screening program is not delivered systematically and correctly across the whole pathway, there is the potential to cause harm at a large scale. Either by falsely reassuring people that they are disease free or advising them they need further testing. The criteria for a screening program include: · It has to be an important health condition · There has to be a ‘good enough’ screening test for the illness · There has to be an asymptomatic stage of the illness. People with symptoms should not delay going to see their GP. Screening tests are not for people with symptoms. · There has to be an agreed group of people who are invited, systematically for screening · There has to be an acceptable and effective treatment available for the condition being screened for
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| 3. What screening programs do the GHA deliver? | The 12 screening programs that the GHA offers are:
In pregnancy: 1. Screening for infectious diseases infectious diseases: HIV, hepatitis B and syphilis 2. Screening for congenital anomalies: Downs, Edwards and Patau’s syndromes 3. Screening for sickle cell 4. Screening to check the physical development of the baby: 20 weeks Newborn: 5. A physical examination: including hips, eyes, heart and testes 6. A hearing test 7. A blood spot test Older children and adults: 8. Diabetic eye screening: additional screening undertaken during pregnancy 9. Cervical screening 10. Breast screening 11. Bowel screening 12. Aortic aneurism
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| 4. Are blood pressure, dementia or PSA (prostate specific antigen) tests classified as screening programs? | No, these are health check tests.
These are important tests and just because they are not classified as screening programs does not mean that they do not help identify people with disease. It means that these tests are not part of a formal screening program. |
| 5. Will a screening test give me a definite diagnosis or ‘true’ result such as telling me I have cancer | No.
The aim of a screening test, especially for cancer screening, is to identify early indications of a disease. The person then needs to go through more rigorous testing to confirm or rule out the diagnosis. Screening programs are evaluated using statistical concepts: sensitivity, specificity, positive and negative predictive values. Bowel screening is an example: you are sent a ‘poo in a pot’ kit. If this tests positive, you are assessed and invited to attend a colonoscopy. The colonoscopy is the gold standards diagnostic test. Most positive bowel tests do not result in a cancer diagnosis at colonoscopy but, other important medical conditions may be identified including pre-cancerous polyps that can be easily removed before cancer develops.
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| 6. Why don’t you offer the diagnostic test as a screening test? | There are a number of reasons why we do not offer a ‘gold standard’ diagnostic test straight away as a screening test including: acceptability to patients of more invasive procedures, reduced uptake as a result of concern about more invasive procedures and the costs and capacity for delivery of more complicated tests.
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| 7. How can someone develop cancer if they have had a negative result? | There are 2 reasons why someone may have a negative screening test and then develop the illness.
1) False negative: see response below 2) Interval cancer. An interval cancer is usually an aggressive cancer that develops in-between screens. An example is women attending for cervical screening every 3 or 5 years. They may have to attend for screening, have a negative test and then a cancer starts developing the following week or month.
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| 8. If interval cancers can develop, why don’t you screen more frequently? | The time between screens or the screening interval is determined by research studies.
It is a ‘trade off’ between people being offered screening too often, when we then know that they won’t attend, against waiting too long and increasing the chances of a cancer developing to a more advanced stage. |
| 9. What are the possible harms and risks from screening? | There are risks and the potential for causing harm from screening programs.
Examples include the psychological harm of being told you may have cancer when you don’t. There may also be increased risk of physical harm from having further investigations. An example is a colonoscopy following on from a positive bowel screening test. There is a small risk that the bowel can perforate or burst, and this is why all patients with a positive bowel screening test are reviewed prior to having a colonoscopy to ensure that they are well enough to have this procedure. This is why it is important for you to read about what the screening program is offering and the limitations for screening to give informed consent.
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| 10. What does a false negative screening result mean? | A false negative result means that the screening test is negative and someone is not referred for further testing and the reality is that they actually has the illness such as a cancer.
This happens because no screening test is 100% reliable because it is not a typically a full diagnostic test. As the name indicates this is a ‘screening test’ not a ‘diagnostic test’. To ensure we reduce the risk of this happening as much as possible we use screening tests have been through research trials and are internationally recognised as a screening test. In addition, the GHA has a serious incident reporting system, where if someone has had a negative screening test and they are then diagnosed with that illness a case review is undertaken. This includes a review of what happened and when to ascertain if there have been any errors or areas that require improvement across the screening pathway.
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| 11. What does a false positive result mean? | A false positive test result is when the screening test is positive but then further investigations confirm that you do not have the illness being screened for.
An example is a positive bowel screening test. Most people who have a positive bowel screen result do not have bowel cancer. Some have, for example, haemorrhoids or importantly pre-cancerous polyps (adenomas) that can be removed during colposcopy. This then removes the opportunity for the polyps to become cancers in the future.
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| 12. If I have symptoms, should I still go for a screening test? | No. If you have symptoms such as a breast lump or blood in your poo these are symptoms where you should book an urgent GP appointment.
The GHA has well developed pathways to investigate people when they have symptoms. Do not wait to be called for a screening test if you have symptoms. Screening tests aim to detect early-stage disease in people without symptoms.
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