Thyroid nodules
About 5% are malignant.
The most common types of thyroid cancer seen are:
 | Papillary cancer |
| Follicular cancer |
With modern treatments the outlook for patients with thyroid cancer is very good and many people are completely cured.
Rarer types of cancer include:
| Medullary cancer - this may run in families. It may also be associated with abnormalities in other body glands (such as the parathyroid glands or the adrenals). |
| Lymphoma - usually in elderly patients and in those who have had Hashimotos's disease. Surgery is not often required and treatment involves chemotherapy and radiotherapy. |
| Anaplastic cancer - this affects elderly patients. It is more common in women and tends to grow more rapidly than the other cancers. |
Confirming the diagnosis
Ultrasound scan: this will tell if the lump is truly solitary and whether it is solid or a cyst. It cannot reliably tell the difference between a benign and malignant lump.
Fine needle aspiration cytology: this test involves pushing a small needle into the lump at sucking out some cells with a syringe. It can be done in the clinic. The cells are then looked at under a microscope to check for the presence of any cancer cells.
Thyroid radioisotope scan: this is only useful in a patient with a nodule who is thyrotoxic (overactive thyroid) and is considered for surgery. A small amount of radioactive substance (technetium) is injected into an arm vein. After 20 minutes a special gamma camera is positioned over the neck. This camera measures the amount of radioactivity in the thyroid gland. Cancerous lumps do not normally take up the radioactive substance and appear as 'cold areas'.
Open biopsy: this essentially means taking the lump out and looking at it under a microscope.
Indications for surgery on a thyroid lump
| evidence of cancer on fine needle aspiration cytology |
| clinical suspicion of malignancy |
| pressure signs or symptoms (difficulty swallowing or breathing) |
| patient preference - cosmetically a problem or causing anxiety |
| thyrotoxic |
| progressive enlargement in a retrosternal goitre (extending into the chest) |
| discomfort in a goitre |
Treatment
Surgery: see section on thyroid surgery for details on the operation.
| Most papillary cancers need total thyroidectomy as they can be multifocal (grow in a number of locations in the thyroid at the same time). |
| Most follicular cancers are treated with total thyroidectomy. The tend to be less multifocal but spread along the blood stream. If the tumour is small and shows minimal invasion of its capsule, a lobectomy is all that is requires. |
| Medullary cancers need total thyroidectomy. |
| Anaplastic cancers sometimes cannot be removed. Surgically decompressing the trachea is sometimes all that is possible. |
Radioactive iodine: Sometimes it is not possible to remove every single cancer cell by means of surgery in patients with papillary cancer. These patients will be given a large dose of radioactive iodine (iodine-131) to destroy the remaining cancer cells. This treatment relies on the fact that the thyroid cells (normal and cancerous) take up the radioactive iodine under the influence of thyroid stimulating hormone (TSH). It works best, therefore, if the patient has not had thyroxine for a few weeks when TSH levels will be at their highest. Radioiodine is not so often given to patients with follicular cancer.
Thyroxine: It is believed that the rate of growth of papillary and follicular cancers of the thyroid may be increased by TSH. Treatment with thyroxine will decrease the levels of TSH. Enough thyroxine is given to make the levels of TSH undetectable.
Follow up
Once treatment is finished the patient will have regular checkups. Blood tests to ensure adequate treatment with thyroxine and to look at thyroglobulin levels (increasing levels may indicate recurrent disease). A radio-iodine scan may indicate the presence of cancer cells in the body.
The British Association of Endocrine Surgeons (BAES) has published its guidelines for the treatment of thyroid cancers. Please see www.baes.org