Thyroid cancer

The thyroid is an endocrine gland shaped like a butterfly. It is located in the neck, in front of the trachea (the wind pipe), and weighs between 18 and 60 grams.

Two hormones called thyroxine (T4) and triiodothyronine (T3) are produced in the thyroid. They control the speed of our metabolism. The more hormones the thyroid produces, the faster our metabolism will work. Both a lack of thyroid hormones and an overproduction of hormones need to be treated.

A person with a lack of thyroid hormones (hypothyroidism) will experience a slow-down of their metabolism, with fatigue and sleepiness, intolerance to cold, slow heart-beat, dry, scaly skin, dry and rough hair, weight gain and water retention, constipation, and even depression. Most patients have several or even many of these signs, but sometimes there are only one or two. Treatment of hypothyroidism is fairly easy: Supplementation of iodine - the substance necessary for the production of thyroid hormones - in the early stages, or supplementation of thyroid hormones in the later stages, given as tablets every day as a life-long medication.

An overactive thyroid, which produces too much of the thyroid hormones, shows the opposite signs (hyperthyroidism): Rapid or even irregular heart-beat, an intolerance to heat, sweating, high muscle tone with cramps, sleeplessness, weight loss in spite of increased appetite, shortness of breath, hair loss, diarrhea, irritability and anxiety, high blood pressure, and shaking. Again, most patients show several of these signs. Treatment consists of medications that suppress thyroid hormone production, or surgical removal of parts of the thyroid gland. Another possibility is destroying thyroid tissue via radiation (see below).

The thyroid hormones contain iodine, an essential trace element found in food. The thyroid collects iodine and uses it for its hormone production. A lack of iodine over a long time often induces the thyroid to grow, in a desperate attempt to catch any iodine atom it can possibly get hold of. This enlargement of the thyroid is called goiter. Lack of iodine - with or without thyroid enlargement - is the most common cause of lack of thyroid hormones (hypothyroidism).

Since the thyroid is the only organ in the body that needs and collects iodine, this can also be used as a treatment. An overactive thyroid can be irradiated from within, by giving the patient radioactive iodine as a medication (a pill or a drink). The radioactive iodine will be concentrated in the thyroid at a very high dose, and there irradiate and destroy the overactive cells.

Thyroid cancer is the most common tumor of any endocrine glands. There are about 140,000 new cases world-wide every year, and this is one of the few cancer types that are increasing in number. About three times as many women as men get thyroid cancer.

One cause of thyroid cancer seems to be iodine deficiency, which roughly doubles the risk of this disease. Another important cause is accidental irradiation with radioactive iodine, particularly if this occurs at an early age, at a dose too low to destroy the thyroid cells completely (like radioiodine therapy) but large enough to damage them. After nuclear accidents, exposure to radioactive iodine in the areas affected by nuclear fallout has been shown to increase the rates of thyroid cancer later.

Thyroid cancer is typically found as palpable nodules in the thyroid. These nodules do not produce thyroid hormones, that's why they are sometimes called "cold" nodules as opposed to overactive, hormone-producing "hot" nodules. There are three major groups of thyroid cancers based on the origin of the tumor cells and the tumors clinical behavior. The so-called differentiated type (papillary or follicular) represents approximately 94% of newly diagnosed cases. The medullary type and the anaplastic type are less common, each representing approximately 4% and 2% of newly diagnosed cases respectively.

Treatment of thyroid cancer differs between these types but almost always includes surgical removal of part of or the entire thyroid gland. After surgery, the remaining thyroid tissue can be destroyed via radio-iodine therapy (see above) in differentiated thyroid cancer.

Bayer is currently investigating an anti-cancer drug for the treatment of patients with differentiated thyroid cancer that is locally advanced or spread distantly and is not likely to benefit from further radio-iodine therapy. This drug is applied as a tablet twice a day, and it is already approved in more than 100 countries for the treatment of kidney and liver cancer.

Advice for patients
Every body reacts differently to medicines. Therefore it is impossible to tell which medicine works best for you. Please consult your physician.