Blood tests

There is no blood test to detect melanoma in the blood stream, although tests are being developed. Blood tests may be carried out to check your general health and to see whether there are any indicators that further tests may be needed.

Chest X-ray

A chest X-ray may be undertaken if further surgery is needed, or because of your past medical history. It may be undertaken if you have the type of tumour that is more likely to spread.

CT or CAT scan

Computerised tomography (CT or CAT scan) is a type of X-ray that creates a picture of a cross-section, or slice, of the inside of the body. It gives a clear picture of soft tissue such as the liver [lymph glands] and blood vessels, as well as bone. You lie on a special couch while it moves through a large hollow ring. X-rays pass through your body, and a picture is displayed on a TV screen. Many pictures may need to be taken, but each one takes only a few seconds.

An hour beforehand you will be asked to drink a liquid contrast medium, which shows up on X-ray. Half way through the scan (which takes between 10 to 30 minutes) you may be injected in the arm with more contrast medium that will show up the veins in your liver. This may make you flush hot all over for several minutes. Your doctor will tell you about what to expect beforehand.

CT scanning can help tell whether the disease has spread to other parts of your body.
The dose of X-ray radiation is more than for an ordinary X-ray, but still within levels considered a low risk, and so a CT scan is regarded safe. Rarely, some people are allergic to the dye, but this can be treated straight away.

Biopsy of lymph nodes or other tissue

If melanoma has spread, the most likely site for this is local draining glands known as lymph nodes (for example, in the armpit for a melanoma on the arm). If your doctor can feel an enlarged lymph node, a sample of cells may be taken for further examination under a microscope (biopsy). The sample is taken through a syringe (fine needle aspiration cytology or FNAC ). The needle may need to be inserted several times. An anaesthetic is not usually needed. The result is accurate, and you will get the result within three or four days. Occasionally a little local anaesthetic is injected and a sample is taken by cutting out the node or a sample from it (open biopsy).

Sentinel lymph node biopsy

In some cases, usually with patients with higher risk melanomas, a dye may be injected at the time of surgery (wide local excision) and a lymph gland removed at the time. This is a procedure called sentinel lymph node biopsy. It is a new test to check whether the cancer has spread to the lymph glands (nodes). It is not a routine treatment as it is still being evaluated, but it may be felt to be appropriate for some patients. If it is performed, then it is usually at the time of a wider excision procedure, and in patients who do not have enlarged lymph nodes.

Lymph nodes help to filter and fight infection. The sentinel node is a funnel to the rest of the glands in the area. It is the first to filter fluid from the area of the tumour. If the sentinel node is clear of melanoma cells, it is very unlikely the cancer has spread beyond it.

Before the operation, lymphoscintigraphy is used to identify the lymph group the tumour drains in to. The first node seen to take up the tracer is identified as the sentinel node. This is detected with a hand-held gamma probe. During the operation a special blue dye is injected into the site of the primary tumour. Together, the dye and the radioactive solution give a double tracing of the branches of the nearby lymph system. This lets the surgeon pinpoint the sentinel node. For the biopsy, a half-inch cut is made to find and remove the blue-stained sentinel node.

The removed tissue is then examined under a microscope. In some cases the result may be known during surgery, but you may have to wait for up to a week. If the results show cancer cells are present, the rest of the lymph glands in the area will need to be removed. There is a possibility that the cancer has spread to other lymph glands, even though the sentinel node is clear, but this is very unlikely.

Ultrasound scan

You may have an ultrasound scan of your lymph glands or liver.

Bone scan

If your symptoms point to possible bone disease, a bone scan may be done. A small amount of radioactive substance is injected into a vein. It travels through the blood stream and collects temporarily in the bones. An instrument called a scanner picks up a picture from the radiation and creates images of the bones on a computer or onto film. This can show whether cancer has spread to the bones.

MRI scan

A magnetic resonance imaging (MRI) scan uses powerful magnetic waves to make a picture of the soft tissue, organs and bones of your body. It does not use X-rays. It can give greater detail than a CT scan.

The machine is a large, tubular ring. You will be asked to lie on your back on a hard couch that passes through the ring. With the help of a computer, pictures of slices through your body are taken. Depending on how many pictures are being taken, you may have to lie still for up to an hour in an enclosed space. If this worries you, tell the radiographer. When it is switched on the machine is very noisy, so you will be given ear-plugs or head-phones to wear. You may also be offered the opportunity to listen to a CD of your choice.

Positron emission tomography (PET)

PET is not used routinely. In some rare cases PET scanners may be more sensitive than CT scanners for detecting whether the melanoma has spread.