Thyroid

Thyroid Cancer: Description

Thyroid diseases are very common in Germany. About every fourth person in Germany has benign nodes in the thyroid gland. Thyroid cancer is rare. About one in every 30,000 people suffer from thyroid cancer each year. There are predominantly women affected by thyroid cancer. There are only inconspicuous symptoms, so a thyroid carcinoma is usually accidentally discovered by an ultrasound. For a reliable diagnosis of thyroid cancer, however, the ultrasound examination alone is not enough.

If the doctor classifies a thyroid nodule by ultrasound as conspicuous, further examinations, such as scintigraphy and possibly a thyroid gland sampling with a fine needle biopsy, follow. In addition, in the case of suspected thyroid cancer, various levels of blood are measured. The specimen from the fine needle biopsy is examined by a pathologist under the microscope. This can detect if it is thyroid cancer. In the thyroid there are different cells with different tasks. Depending on the cell type of the tumor, a distinction is made between different types of thyroid cancer.

The four most common types of thyroid cancer

The majority of thyroid carcinomas can be assigned to one of the following four types. They differ with regard to their treatment and prognosis:

• papillary thyroid carcinoma: About 60 percent of all cases of thyroid cancer
• follicular thyroid carcinoma: about 30 percent
• Medullary thyroid carcinoma (C-cell carcinoma, MTC): about 5 percent
• Anaplastic thyroid carcinoma (undifferentiated thyroid carcinoma): about 1 percent

One papillary thyroid carcinoma is the most common type with about 60 percent of all cases of thyroid cancer. Women are significantly more likely to be affected by papillary thyroid cancer than men. The cancer cells spread preferentially via the lymphatic system (lymphoid metastasis), so that the lymph nodes on the neck are often affected as well. With adequate therapy, papillary thyroid carcinoma can be cured in about 80 percent of cases (ten-year survival).

The follicular thyroid carcinoma makes up the second most common type about 30 percent. A follicular thyroid carcinoma mainly affects women. The spread of cancer cells occurs predominantly via the blood (hematogenous metastasis), so that the cancer cells often spread to the brain or into the lungs. Although the chances of recovery are slightly worse than those of papillary thyroid cancer, the ten-year survival after treatment is still around 60 to 70 percent.

The medullary thyroid carcinoma (also called C-cell carcinoma) does not start from the actual thyroid cells (thyrocytes), but develops from the so-called C-cells. These cells produce the hormone calcitonin, which is very important for the regulation of the phosphate and calcium balance. In a medullary thyroid carcinoma there is a massive overproduction of calcitonin by the tumor. This leads to a decreased calcium value in the blood, which can be manifested by emotional disorders. In addition, medullary thyroid cancer typically has severe diarrhea. Contrary to popular belief, these diarrhea are not due to increased calcitonin levels but are the result of certain substances produced by the tumor (“vasoactive substances”). Causes of medullary thyroid cancer may include various gene mutations (see Causes and risk factors). Men and women are equally affected in this type of thyroid cancer. The ten-year survival rate is around 50 to 70 percent.

The Anaplastic thyroid carcinoma is the rarest type of thyroid cancer and clearly different from the others. It grows very fast and aggressive and is therefore hardly curable. Women and men are equally affected by this thyroid cancer. The life expectancy of anaplastic thyroid carcinoma is very low. After being diagnosed, those affected live on average for about six months.

Thyroid cancer: symptoms

Read all about the typical signs of thyroid cancer in the article Thyroid Cancer – Symptoms.

Thyroid cancer: causes and risk factors

The causes of thyroid cancer are still not clear. Contrary to popular belief, iodine deficiency does not appear to be a risk factor for its development. However, in the iodine-rich areas, a prognostically more favorable papillary thyroid carcinoma tends to occur. There are different causes and risk factors for the four types of thyroid cancer:

Papillary and follicular thyroid carcinoma

There is strong evidence that these two types of thyroid cancer are triggered by ionizing radiation. For example, after the Chernobyl nuclear reactor accident, about 1,500 children in Belarus, Ukraine and Russia contracted thyroid cancer. Survivors of the atomic bombing of World War II cities in Hiroshima and Nagasaki in Japan also developed significantly more common thyroid cancer. Even after radiotherapy for therapeutic reasons, for example, in a lymphoma or a tumor in the head and neck area, there is an increased risk for the development of thyroid cancer.

Medullary thyroid carcinoma

In about 25 percent of those affected by medullary thyroid carcinoma (C-cell carcinoma), a genetic defect is the cause of the disease. There are several gene modifications (mutations) in the RET gene on chromosome 11. These can result in either medullary thyroid carcinoma occurring alone or in combination with various other diseases. In the latter case one speaks of a so-called multiple endocrine neoplasia (MEN, type 2). People with this gene mutation are very likely (> 90 percent) to develop a medullary thyroid carcinoma, which is why the thyroid gland is removed as a precaution in childhood (prophylactic thyroidectomy).

Anaplastic thyroid carcinoma

The causes and possible risk factors for the development of anaplastic thyroid carcinoma are still completely unknown.

Thyroid cancer: examinations and diagnosis

Abnormalities of the thyroid are usually altered by blood values or in the ultrasound obviously. These investigations are mostly carried out by Specialist in General Medicine or the Specialist in internal medicine accepted. The thyroid hormones T3 and T4 (also commonly referred to as fT3 and fT4) and the hormone TSH (thyroid stimulating hormone) are measured in the blood. If the measured values ​​deviate from the norm values, the ultrasound examination of the thyroid usually follows. With the ultrasound the doctor can already see if the size and structure of the thyroid have changed. For example, he can determine if there are nodules in the thyroid gland and the thyroid gland is enlarged (“goiter nodosa”). As part of the investigation, the doctor may also palpate the thyroid gland and ask various questions medical history (Anamnesis):

• Are thyroid disorders known to your parents or siblings? If yes, which?
• Have you been previously treated for another cancer?
• Do you have problems swallowing or breathing?
• Have you noticed swollen lymph nodes or other peculiarities such as pain or redness of the skin in the neck area?
• Were you potentially exposed to ionizing radiation, for example for work or residence in the vicinity of a radioactive contaminated area (eg Chernobyl in Ukraine or Fukushima in Japan)?

Around one in four people in Germany have nodules in the thyroid gland. However, only 0.2 percent of these nodules are thyroid cancer. Although the doctor can already gather information about whether it is benign nodules or malignant thyroid cancer in the ultrasound – further investigations are necessary for a reliable diagnosis. Since thyroid cancer is rather rare, many doctors first observe the development of the nodes over several weeks and look at the thyroid gland again and again in the ultrasound. If, due to ultrasound, the doctor classifies the nodes in the thyroid gland as potentially carcinogenic, or if the nodules have a diameter of more than one centimeter, further examinations are carried out:

Further investigations in case of suspected thyroid cancer

The next step in Germany is usually the thyroid scintigraphy used. She is from one nuclear medicine carried out. It is used to clarify conspicuous nodules that were previously found on ultrasound. First, a radioactive substance (usually sodium 99mTechnetium pertechnetate) is administered via the vein. The radioactive substance is also called a “tracer”. The radioactivity of the tracer is very low and has only a short half-life, which is why the negative effects on the body are considered to be very low.

The tracer is structurally similar to the iodide, which is taken up into the thyroid gland for the production of thyroid hormones. Therefore, the tracer accumulates exclusively in the thyroid gland. The more active the thyroid cells (thyrocytes) are, the more iodide or tracer they absorb. The radioactive radiation of the tracers can be recorded by a special camera (gamma camera). This gives an image of the thyroid gland, which says something about the structure and especially the function of the thyroid gland. In places of particularly high activity of the thyroid cells, there is also a particularly strong accumulation of radioactive tracers. These areas are usually shown in red in the image of thyroid scintigraphy. In contrast, areas of low activity in blue and green color.

Now the doctor compares the images of the thyroid of ultrasound and scintigraphy. If in an area of ​​the thyroid gland, in which a suspicious node has already been found in the ultrasound, there is also noticeably reduced or missing activity in the scintigraphy.cold knot“(Dark color in the scintigraphy picture, low or missing activity). A cold knot may or may not be an indication of thyroid cancer. With only about three to ten percent of the cold nodes, thyroid cancer is present. Highly active nodes, on the other hand, are referred to as “hot knots” (red color, strong activity). These can occur, for example, in a benign hyperthyroidism (autonomous thyroid adenoma), but are not a sign of thyroid cancer.

A cold knot should in any case by a Fine needle biopsy (FNB) be checked. It is inserted under ultrasound control with a fine needle into the thyroid into the area of ​​the cold knot (puncture) and thyroid tissue removed. A local anesthesia is usually not necessary because it is a one-time puncture. An anesthetic injection would also require a puncture and therefore offers no advantage. In order to avoid bleeding through the puncture, it should be discussed with the doctor beforehand which medicaments may need to be discontinued in good time before the puncture (for example, blood-thinning medications such as aspirin, marcumar, etc.).

The collected sample material is submitted to a pathologist for a histological examination. He tries to answer if it is thyroid cancer or not. However, this is sometimes very difficult, so even the pathologist can not always make a clear diagnosis. If the diagnosis is thyroid cancer, first of all various investigations are carried out to determine how far the thyroid cancer has already spread (staging examinations). These include ultrasound, an X-ray of the chest, computed tomography (CT) and magnetic resonance imaging (MRI). Subsequently, the patient is operated on as soon as possible.

In addition to the diagnostic steps mentioned so far, suspected thyroid cancer is often accompanied by a single measurement of the calcitonin value in order to exclude a medullary thyroid carcinoma. Medullary thyroid carcinoma produces large amounts of the hormone calcitonin, which is measurable in the blood. A calcitonin value of more than 20 picograms per milliliter (pg / ml) is noticeable in each case.

Thyroid cancer: treatment

Choosing the right form of treatment for a thyroid carcinoma depends on the type of thyroid cancer present and how far the cancer has spread in the body. Usually, first, the thyroid gland is partial or complete surgically removed (Thyroidectomy). After that takes place in papillary and follicular thyroid cancer radioiodine therapy to remove residual tissue of the thyroid gland.

Radioiodine therapy is used to administer radioactively labeled iodine to the patient. The radioactive iodine accumulates exclusively in the metabolically active thyroid cells and destroys them. The complete elimination of thyroid tissue is important for the follow-up of thyroid cancer, as this can quickly detect any recurring thyroid cancer: thyroid tissue produces, inter alia, the protein thyroglobulin (TG). After surgery and radioiodine therapy, no thyroglobulin should be measurable in the blood. On the other hand, if it becomes measurable again over the years, this is a sign of a recurrence (recurrence) of thyroid cancer. Radiation from the outside (radiotherapy) is not very effective and is only used to reduce metastases in severe pain. In addition, the tumor cells in thyroid cancer hardly respond to chemotherapy (cytostatic drugs), which is why it is also used only in extensive metastases. The different types of thyroid cancer are treated differently:

Papillary thyroid carcinoma

If there is no evidence of daughter dislocations (metastases) in the lymph nodes and if the tumor is not larger than 1.5 centimeters in diameter, usually a removal of the affected thyroid lobe (Hemi-thyroidectomy) and the removal of cervical lymph nodes. However, if the papillary thyroid carcinoma is larger and poorly demarcated from surrounding tissue, the entire thyroid gland is removed (total thyroidectomy). About 10 to 14 days after the operation closes the radioiodine therapy at. Thereafter, a high dose of thyroid hormone (thyroxine, T4) must be taken for life with papillary thyroid cancer. The dose deliberately goes beyond what is necessary. This is to suppress the release of the hormone TSH (suppressed). The release of TSH would stimulate any residual cells of the tumor to grow.

Follicular thyroid carcinoma

In follicular thyroid carcinoma, regardless of the size of the tumor, the entire thyroid gland is removed (total thyroidectomy). As with papillary thyroid carcinoma, radioiodine therapy follows after surgery. In addition, the TSH secretion is also suppressed by the intake of high-dose thyroid hormone (thyroxine).

Medullary thyroid carcinoma (C-cell tumor)

The treatment of choice for a medullary thyroid carcinoma is also the complete surgical removal of the thyroid gland (total thyroidectomy). Radioiodine therapy, on the other hand, does not make sense because C cells do not store iodine. The dosage of thyroid hormone (thyroxine) in the medullary thyroid cancer after the operation in a normal high range, which should only cover the need, but should not inhibit the release of TSH. The strong diarrhea can hardly be controlled with the usual drugs, so sometimes an opioid-containing solution is used (“Tinctura opii”).

Anaplastic thyroid carcinoma

Surgery is usually not useful for anaplastic thyroid cancer due to the very poor prognosis. Usually external radiation (radiotherapy) is used to reduce the size of the tumor and to relieve the local symptoms (feeling of pressure when swallowing, breathing difficulties). The extent to which chemotherapeutic agents are effective in anaplastic thyroid carcinoma is currently being tested experimentally.

Thyroid cancer: disease course and prognosis

Thyroid cancer healing and life expectancy depend on what type of thyroid cancer is present and how far the disease has progressed.

Thyroid cancer: life expectancy

People with papillary thyroid carcinoma have the best cure prospects compared to the other types of thyroid cancer. Ten years after the treatment, more than 80 percent of those affected still live. Follicular thyroid cancer also has a relatively good prognosis: the ten-year survival rate is about 60 to 70 percent. A slightly worse prognosis people have with medullary thyroid cancer, Here, the ten-year survival rate is only about 50 to 70 percent. The Anaplastic thyroid carcinoma Unfortunately, according to the current medical status, it is virtually impossible to cure. The median survival time after diagnosis is only six months. It should be noted, however, that these are average values, which in individual cases may differ significantly from the times given here.

Aftercare for thyroid cancer

In order to detect a recurrence of thyroid cancer (recurrence) as early as possible, regular follow-up examinations should be carried out. This includes a regular examination of the neck region with ultrasound. In addition, various laboratory values ​​can be measured, which are produced only by thyroid gland tissue and therefore speak for a completely rebuilt thyroid gland for a renewed tumor growth. These laboratory values ​​are also referred to as so-called tumor markers. In particular, calcitonin (medullary thyroid carcinoma) and thyroglobulin (papillary and follicular thyroid carcinoma) are included as tumor markers for follow-up Thyroid significant.