What is goiter?
Goiter is the enlargement of the thyroid, which is a butterfly-shaped gland in front of the neck. If this is a simple enlargement of the otherwise normal goiter it is called simple or diffuse goiter. If it is due to the enlargement of the nodules inside the goiter it is then called nodular goiter.

What are the types of goiters?
Goiters may be due to iodine deficiency or autoimmune thyroiditis which is called Hashimoto thyroiditis. In iodine deficiency, there is insufficient amount of iodine in the blood and thus thyroid hormone levels are low. In autoimmune diseases, hormone production is decreased because there are antibodies against the thyroid. In both conditions, thyroid hormone levels are decreased, and to compensate for this, our body increases the secretion of thyroid stimulating hormone (TSH) which is released from the pituitary gland. This hormone stimulates the thyroid and increases its size to produce more hormones. The result is homogenous enlargement of the thyroid, which is called simple goiter.

In nodular goiter, thyroid is enlarged due to the presence of nodules. These nodules may be single or multiple, cystic or solid and in terms of hormone production, hot, warm or cold. Hot nodules produce more hormones then the normal thyroid tissue. And as a result, they look active on scintigraphy. Cold nodules do not produce hormones and they are seen as inactive areas on scintigraphy. Warm nodules produce the same amount of of hormones as the normal thyroid and thus, moderately active on scintigraphy.

Sometimes there are many nodules in the thyroid and this condition is called multinodular goiter (MNG), which is one of the commonest disorders of the thyroid. In MNG, the thyroid is enlarged due to presence of multiple nodules of various size. Sometimes these nodules may become very large and compress the trachea (windpipe) causing shortness of breath. In this condition, which is also called plunging goiter, there may also be voice changes, swallowing difficulties and upper eyelid paralysis (Horner syndrome) due to sympathetic nerve dysfunction.
 

Multinodular goiter and cancer
In multinodular goiter, surgery is generally recommended due to the possibility of risk of cancer in one of the nodules. In fact, it has been shown that in up to 8 to 10% of MNG patiens there may be small cancer foci in the thyroid. However:

All these small foci are papillary cancer (papillary microcarcinoma) which is the best type of thyroid cancer. These tumors are extremely slowly growing and some centres even prefer not to treat them.

In some autopsy studies, these small cancer foci were also seen in the thyroid gland of normal individuals who have died for reasons other than thyroid cancer. This shows that small papillary cancers can be seen in many normal people, but they are clinically not very important.

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• In famous "Framingham" study, a large number of MNG patients who have a total of 218 thyroid nodules have been followed up for 15 years, and none of these patients have developed thyroid cancers. This shows that the risk of cancer development in MNG patients is very low despite the presence of multiple nodules.

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In conclusion, scientific studies suggest that the risk of MNG patients having thyroid cancer seems to be similar to those of normal individuals. Surgery is an important treatment in MNG, but systematic surgical operation of all MNG patients just for the small risk of cancer is not based on any scientific data. Therefore, this approach should be abandoned.

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How must goiter be treated?

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In simple goiter, the treatment must be to replace what is lacking. If there is iodine deficiency, iodine must be taken with diet or medications. If there is hormonal deficiency due to autoimmune thyroiditis, then the thyroid hormone pills must be taken. In this way, since the hormones are given externally, the thyroid will not have to work to produce hormones, and thus its size will not be enlarged. 

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In nodular goiter, first we must investigate whether the nodules are benign or malignant. For this, first a thorough ultrasound examination must be done and the number, size, texture and location of the nodules be determined. If the patient has hyperthyroidism, a scintigraphy must be performed to demonstrate the activity (hot, cold or warm) of the nodules. Ultrasound examination is very important to select the suspicious nodules for  biopsy. In general, large, grey, solid nodules with small calcifications, irregular borders and vertically oriented long axis are more likely to be cancer. Such nodules must be biopsied with fine needle aspiration or trucut biopsy. If the result is benign, the patient may either be treated or followed up; If the nodule is small and does not cause any symptoms regular follow up is recommended, but if it is large, continuously growing or creating symptoms then treatment is necessary. Although surgery is frequently offered for such patients, percutaneous ablation and embolization are increasingly preferred because of their important advantages.

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Classic treatments of multinodular goiter (MNG)

These treatments include oral medications, radioactive iodine and surgery.

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In oral medications, thyroid hormone (T4) containing pills are given to the patients. In this way, the thyroid functions are lowered and the gland may not grow or even shrink. However, this shrinkage (if any) is generally very modest and is seen in only 1/3 of the patients. Besides, externally given thyroid hormone pills may cause subclinical hyperthyroidism and create heart problems. Additionally, if used for a long time, they may cause osteoporosis, which may be very dangerous particularly in postmenapausal women, leading to compression fractures. For these reasons, oral medications are not regarded an attractive treatment option in patients with MNG.

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Radioactive iodine is a noninvasive and easy-to-apply treatment in various thyroid disorders. Many studies show that thyroid shrinks %15-60 1-2 years after the treatment and hyperthyroidism may heal or get better. However, following the radioactive iodine hypothyroidism may develop and the patient may have to take lifelong medication. The side effects of this medication are cardiac problems such as arrhytmia and osteoporosis. Besides, in MNG patients, it is necessary to give a high dose of radioactive iodine and this may increase the risk of cancer in the future.

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Surgery is one of the most frequently used treatments in MNG patients. Although it is a radical and successful treatment, it requires general anesthesia, a longer hospital stay and causes an unpleasent scar in the neck. It also has important risks including recurrent laryngeal nerve injury (causing voice loss) and hypoparathyroidism (causing calcium metabolism disturbance). Besides, since the whole gland is surgically removed, the patient has to take lifelong thyroid medications which may cause heart problems and osteoporosis.

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In conclusion, each classic goiter treatment has specific disadvantages and side effects. Therefore, new treatment options that preserve thyroid gland and have little side effects are necessary.

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New nonsurgical treatments in multinodular goiter (MNG)

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In MNG patients, new options such as percutaneous ablation and embolization has been increasingly used in the last 2 decades. In percutaneous ablation, special needles are inserted through the skin into the nodules and the nodules are destroyed with several methods. These include thermal ablations (laser, radiofrequency, microwave) and alcohol. After perfutaneous ablation, the treated nodules shrink significantly and their symptoms such as hoarseness, shortness of breath and swallowing difficulty may decrease or disappear.

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Video: Laser or RF ablation of thyroid nodules

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In MNG, if the nodules are few, percutaneous ablation must be the first line treatment. However, if the nodules are too many, ablation may take too long and become impractical. In such cases, embolization is a very good alternative. Embolization is especially beneficial in plunging goiters that extends into the chest cavity and compress the trachea (windpipe) causing shortness of breath. In this treatment, the vessels that feed the goiter are occluded using small particles. After this treatment which is quite easy and safe, the part of the thyroid gland which is filled with nodules become smaller but does not lose its viability. The procedure is done under local anesthesia using special angiography equipment. The patient may leave the hospital the following day. Embolization has following advantages over the other treatments for multinodular goiter:

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• Unlike surgery and radioactive iodine treatment, no hypothyroidism develops after the procedure. Thus, the patient will not have to take lifelong hormone pills and suffer from their side effects.

• There is no high dose radiation exposure and related problems.

• There are no complications such as surgical scar, voice loss, hipoparathyroidism.

• It is an effective treatment. Following embolization, a 70-90% volume reduction of the goiter mass can be achieved. As a result, compressive complaints such as shortness of breath, hoarseness and swallowing difficulty decrease or disappear.

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Video: Why we treat large nodules and goiter with embolization?

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Video: How is embolization performed?

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