A B C D E F G H I J K L M N O P R S T U V W

THYROID GROWTHS - THYROID CANCER

What are Thyroid Growths ?

The thyroid gland is found low in the neck and is shaped like a butterfly. It makes two hormones, thyroxine (T4) and triiodothyronine (T3), which are released into the blood circulation. The hormones control the speed of all the body's functions (or metabolism). As with any other organ, the thyroid may be the site of growths (tumours). These are mostly benign (non-cancerous), but can be malignant (cancerous). Most lumps in the thyroid are due to cysts or other benign irregularities of the gland. Such growths may be first seen or felt as a lump in the neck. They may also cause difficulty in swallowing by pressing on the gullet, or even shortage of breath by pressing on the windpipe. Thyroid growths do not usually cause pain. Occasionally benign growths will overproduce thyroid hormones (hyperthyroidism). This is called toxic adenoma or nodular toxic goitre. These conditions produce the symptoms of palpitations, trembling, weight loss and sweating. Rarer types of malignant thyroid growths (called medullary tumours) produce a different hormone, calcitonin. This has no observable effects on the body. However, another hormone (called adrenocorticotrophic hormone: ACTH) produced by this tumour can stimulate the adrenal gland to produce a condition called Cushing's syndrome.

How do Thyroid Growths occur ?

Like other growths, thyroid tumours begin as a few cells which multiply more rapidly than normal thyroid cells. Benign growths enlarge only slowly and do not spread outside the thyroid gland itself. Malignant growths usually grow more quickly and spread to lymph glands in the neck. Occasionally they may spread to other organs as wel through the blood stream.

Why do Thyroid Growths occur ?

It is not known what causes any form of thyroid growth. However, some people who have been exposed to high doses of radiation (for example in Hiroshima after the atomic explosion) have developed malignant tumours many years later. The tendency to thyroid growths is not inherited. However, the rare medullary thyroid cancer (which produces the hormone calcitonin) often occurs in relatives of the patient as well, and this may be a reason for screening family members.

Treatment involved for Thyroid Growths

Once a lump appears in the thyroid, special tests are carried out. Ultrasound (like a radar system using sound waves) can give some information about the size of the growth. A thyroid scan (using a harmless dose of radiation) allows a picture of the thyroid to be obtained which is helpful to the doctor. A small sample of the thyroid lump can be taken (aspiration cytology). This is done by putting a fine needle into the thyroid after injecting local anaesthetic. Cells are sucked into the needle and can then be examined under the microscope. Blood tests are also usually done to measure all the relevant hormones. If the tumour is found to be benign, it may be removed by operation. Small benign growths which are not causing any discomfort may be left happily alone. If it is one of the benign growths which is overproducing thyroid hormones, it is sometimes treated by operation as well. However, a single dose of radioactive iodine can be given by mouth. This destroys the overactive thyroid cells, without damaging normal thyroid tissue. If a growth is found to be malignant, an operation is always necessary. Sometimes the whole thyroid needs to be taken away. If any other structures in the neck are affected, these need to be removed as well. To find out if malignant growths have spread, a whole body scan is performed after the thyroid has been removed by operation. For this, a dose of radioactive iodine is given. This will be absorbed into any thyroid cells which may have scattered through the body. Using sensitive equipment, the whole body is scanned to see whether there are such groups of abnormal thyroid cells. If any are located, a bigger (but quite safe) dose of radioactive iodine can be given. This will also be absorbed into the abnormal thyroid cells and will destroy them. Rarely, ordinary x-ray treatment (radiotherapy) will be used.

During treatment for Thyroid Growths

The removal of benign growths rarely causes any problems. During treatment of malignant thyroid growths, removal of the whole thyroid gland results in temporary thyroid underactivity (hypothyroidism). This may cause tiredness, weight gain and a dry skin. It is only a passing stage, which the doctor will watch for, and eventually thyroid tablets will be given to correct it. Sometimes the parathyroid glands, which sit behind the thyroid, are damaged during operation. This results in a low level of calcium in the blood, which requires treatment with vitamin D preparations, often with calcium supplements.

After treatment

Benign growths would probably enlarge little, if at all. Malignant growths would mostly increase in size, cause symptoms by pressure on neighbouring tissues, spread through the body, and ultimately could produce serious illness. However, some malignant growths enlarge very slowly indeed, and do not affect lifespan.

If Thyroid Growths are left untreated

After removal of benign growths, recurrence is most unusual and patients are normally discharged from follow-up. Where such a benign growth has caused an overactive thyroid state, symptoms rapidly settle to normal within 1 to 2 months of either operation or radioactive iodine. Following removal of malignant tumours, regular checks are needed lifelong. Compared with most other malignant tumours, the thyroid type often allows a perfectly normal life-span. Some patients, however, will require extra radioiodine doses. If any unusual symptoms or further swellings occur, the doctor needs to be notified.

Effects on family of Thyroid Growths

The only conditions which are hereditary are the rare medullary thyroid cancers. Since they produce calcitonin which can be measured in the blood, relatives will often have their calcitonin levels measured. This will make it possible to tell whether they have small tumours of this type themselves, which may need operation.