Typical Paths to Diagnosis
NET cancers are difficult to diagnose. The onset of symptoms takes an average of five to seven years, and even then symptoms are often non-specific and vague. If NET cancers are detected early in their development, they can often be cured with surgery. At present however, most NET cancers are diagnosed at a later stage, when they have already spread to other parts of the body. In these cases, they can rarely be cured, although the symptoms can often be managed successfully for a number of years.
NET cancers can give rise to a wide variety of symptoms depending on where they are in the body and the type of cells they originate from. The symptoms may be mild or non-specific, and are often similar to those of other, more common conditions. For example, many of the symptoms associated with carcinoid tumors are similar to those of IBS, Crohn’s disease, peptic ulcer disease, gastritis or other digestive disorders.
Many doctors are unfamiliar with NET cancers and are therefore less likely to suspect a NET cancer in their initial investigations. NET cancers are difficult to detect for a number of reasons:
- Size: they are often small; some NET cancers can be less than a centimetre in size
- Location: NET cancers can occur almost anywhere in the body
- Symptoms: these can vary enormously, and some patients have no symptoms at all
- Testing: there are many different types of NET cancer, and a series of specialised tests is necessary for a definitive diagnosis
There are many tests and scans available that your healthcare team will use to gather information about the NET, its spread and rate of growth.
You may be asked to have a fasting gut hormone blood test, and blood will also be collected for a range of other tests. Doctors look for certain NET markers, particularly chromogranin A and B. Other examples of hormones and peptides that the doctors look for are pancreatic polypeptides, insulin and gastrin, as well as checking how well your kidneys and liver are functioning.
If the results of this test suggest the presence of a NET, further imaging tests will be carried out to confirm the diagnosis.
5-HIAA (hydroxyindoleacetic acid) is a substance that is naturally produced and eliminated by the body. Normally, only small amounts are present in the urine. Elevated levels in a urine sample may indicate a NET, although further tests are required to confirm the diagnosis.
You will be asked to avoid certain foods 24 hours prior to, and for 24 hours during, the test. The foods include chocolate, olives, bananas, pineapple and its juice, all tomato products, plums, aubergine, avocado, kiwi fruit, walnuts, brazil nuts, cashew nuts, tea, coffee and alcohol.
For three to seven days prior to the test you will also be asked to avoid several medicines i.e. certain cough, cold and flu remedies, treatments for high blood pressure, the muscle relaxants e.g. diazepam, monoamine oxidase inhibitors and any natural herbal products purchased in health food shops that produce the same effects as these medicines. This is because all these products naturally contain substances that might artificially raise your 5-HIAA levels and give a false test result.
In this test, a flexible camera, called an endoscope, is used to examine the digestive tract. The tube can be inserted down the back of the throat (gastroscopy) or via the rectum (colonoscopy). In both cases you will be offered sedation.
If abnormal-looking tissues are found during this procedure, a sample can be collected and examined under a microscope. A tissue biopsy like this can be the only definitive test for a NET cancer.
Ultrasound scans use sound waves to build up a picture of the inside of the body. They are completely painless. These scans are usually done in the hospital X-ray department.
The ultrasound scanner has a microphone which gives off sound waves. The microphone is passed over your body and the sound waves bounce off the organs inside your body, and are picked up again by the microphone. The microphone is linked to a computer which turns the reflected sound waves into a picture.
This involves taking a piece of tissue from the suspect tumour and analysing it in the laboratory by a specialist called a histopathologist.
The specialist may review the biopsy sample and give your tumour a ‘proliferative index’ i.e. a measure of the number of cells in the tumour that are dividing (proliferating). A proliferation index of less than 2% means that the tumour is very slow growing, while a value above 10% suggests faster growth.
Being able to look at the tumour under the microscope can be the only way to determine exactly what type of NET cancer it is.
Computerised Tomography (CT) Scan
A CT scanner is a special type of X-ray machine which uses ionising radiation to provide a three dimensional picture of the inside of the body. It can be used to determine the position and size of tumours, and regular scans are useful to find out more about the rate of tumour growth and how the tumour is responding to treatment.
Before the scan, you may be asked to have an injection or drink a fluid containing a dye that shows up on the scan.
Magnetic Resonance Imaging (MRI)
An MRI scan can be used to locate a tumour. Magnetism is used instead of X-rays to produce soft tissue images that can distinguish between normal and diseased tissue.
If a tumour is identified in this way, further tests may be needed to confirm the type of tumour.
These scans use a body imaging technique. Cells that receive hormonal messages do so through receptors on the surface of the cells. For reasons that are not fully understood, many NET cells possess especially strong receptors; for example, GEP-NETs often have strong receptors for somatostatin, a very common hormone.
The OctreoScan uses a synthetic form of somatostatin, which is chemically bound to a radioactive substance. This is injected via a vein in the arm and then observed 24 hours later using a radio-sensitive scan. These scans can diagnose and locate around 80-90% of GEP-NETs, although further scans, such as PET scans may still be required.
There are a many other tests that may be employed in the diagnosis and classification of your NET:
- MIBG Scan
- PET Scan
- Bone Scan
Multidisciplinary Team Approach to Care
Different NETs affect people in different ways in terms of how the tumour grows, the symptoms produced, whether or not they spread and how they spread. Gaining the histology (what the tumours look like under a microscope) is very important in order to classify the cancer into a type, and your healthcare team can then work with you to plan the most appropriate treatment.
Although NETs share similar characteristics, the diagnosis and the way your cancer behaves may be different.
The most important aspect of caring for a person with a NET is that the care should be tailored to suit the individual and provided by a specialist in the field of NETs. Your quality of life is paramount and so team work is essential to provide a solid plan of treatment and follow-up.
There has been much research work done by specialist healthcare professionals, and progress has been made in terms of understanding these tumours. It is important to ensure that you are seen by these specialists in order to access all the knowledge available.
NET cancer care can be complex. For you the journey can encompass not only a whole host of emotions, but also a range of investigations, treatments and healthcare professionals. Often there is more than one treatment option available, and so there has to be a collaboration amongst all key healthcare professional groups who are making clinical decisions for you. This collaboration is called a multidisciplinary team or MDT. The MDT management approach is now being used across the world in the care of people with NETs.
Throughout the NET journey, you may potentially see the following healthcare professionals: