If you have any of the possible symptoms of thyroid cancer, your GP will:
- carry out a physical examination of your neck
- ask you whether you are experiencing any associated symptoms, such as unexplained hoarseness
The next step is to check whether the swelling in your neck is caused by other problems with your thyroid. This is done by carrying out a blood test known as a thyroid function test.
Thyroid function test
The most common cause of swelling in the neck is either an overactive thyroid gland (hyperthyroidism) or an underactive thyroid gland (hypothyroidism). To confirm or rule out these conditions, a thyroid function test may be carried out.
A thyroid function test measures the amount of certain types of hormones in your blood. An excessive amount of the two hormones that are produced by the thyroid gland, thyroxine and triiodothyronine, would indicate an underlying condition that is making your thyroid gland overactive.
If your thyroid gland is underactive, another gland, known as the pituitary gland, will produce a hormone called thyroid stimulating hormone (TSH). TSH is released by your body to stimulate your thyroid gland. Therefore, a high level of TSH in your blood would indicate that your thyroid gland is underactive.
See the Health A-Z topics about Overactive thyroid and Underactive thyroid for more information.
Further testing will be required if the thyroid function test reveals that your thyroid gland is working normally.
Fine-needle aspiration cytology
Fine-needle aspiration cytology (FNAC) is the next stage in diagnosing thyroid cancer. FNAC is carried out as an outpatient. This means you will not have to spend the night in hospital.
During a FNAC, a small needle will be inserted into the lump in your neck. The needle is used to remove a small sample of cells, which are then studied under a microscope. A FNAC can usually reveal whether or not any cancerous cells are present in your thyroid gland and, if they are, what type of thyroid cancer you have.
Further testing
Further testing may be recommended if the results of the FNAC are inconclusive, or if more information is required to make your treatment more effective.
These tests may include:
- repeat FNAC combined with ultrasound scan
- other types of scan, such as a CT or MRI scan
See the Health A-Z for more information about Ultrasound scans, CT scans and MRI scans.
However, in most cases, when it has not been possible to rule out thyroid cancer by FNAC, a thyroid operation will be required to remove the part of the thyroid gland that contains the lump or swelling.
Staging
Staging is how far the cancer has spread through the body; the higher the grade, the further it has spread. It is usually impossible to stage the tumour before the initial treatment has been completed - that is, after surgery and radioactive iodine treatment (see below).
Thyroid cancer can be categorised using a system that is known as the TNM classification where:
- T - indicates the size of the tumour
- N - indicates whether the cancer has spread to nearby lymph nodes (small oval tissues that remove unwanted bacteria and particles from the body)
- M - indicates whether the cancer has spread to other parts of the body (metastasis)
While widely used, the TNM system can sometimes be difficult for someone with little or no medical knowledge to understand. Therefore, for the sake of clarity, the rest of the article will use a staging system that is derived from TNM, where the stages of thyroid cancer are described numerically.
Staging for differentiated thyroid cancers (papillary carcinomas and follicular carcinomas) vary with age, as in older people these types of cancers tend to be more aggressive.
In cases of differentiated thyroid cancers in people under 45 years of age only two stages are used:
- stage 1 - the cancer may have spread to other lymph nodes in the neck or head, but not to another part of the body
- stage 2 - the cancer has spread to other parts of the body
Four stages are used in cases of differentiated thyroid cancers that occur in people over the age of 45, and also for all cases of medullary thyroid carcinoma:
- stage 1 - the tumour is no larger than 2cm across and has not spread out of the thyroid gland
- stage 2 - the tumour is now 2-4cm across but is still contained within the thyroid gland
- stage 3 - the tumour has spread out of the thyroid gland into nearby lymph nodes
- stage 4A - the tumour has spread out of the lymph nodes and into other tissues of the neck such as the muscles of the neck, or spread to the lymph nodes in the upper chest, but not to other parts of the body
- stage 4B - the tumour has spread to the tissue near the spine, but not to other parts of the body
- stage 4C - the tumour has spread to other parts of the body; typically the bones, lungs or both
Staging is not usually used for cases of anaplastic thyroid carcinoma because by the time it is diagnosed, the cancer will have spread to another part of the body.
