Thyroid Cancer

What is thyroid cancer?

The butterfly-shaped thyroid gland, which normally weighs around 20 grams, lies in the front of the neck slightly below the larynx and nestles against the sides of the windpipe with its two lobes. The gland produces and stores the important thyroid hormones triiodothyronine (T3) and thyroxine (T4). These hormones regulate metabolism, but also growth and cognitive abilities.

In addition, certain cells of the thyroid gland, the C-cells, produce the hormone calcitonin. This is involved in the body’s calcium regulation, but is only of secondary importance here.

Thyroid cancer can originate from different cells of the thyroid gland and the cancer cells can be differently differentiated, which has an influence on their growth behavior. The classification of thyroid cancer is based on this, which in turn determines which therapies are appropriate and what course of the disease can be expected:

• Differentiated thyroid carcinoma:
  • Papillary carcinoma, which accounts for the majority of all thyroid carcinomas.
  • Follicular carcinoma, affects less than a quarter of cases.

These two most common forms of thyroid cancer are usually very treatable.

• Little to undifferentiated/anaplastic thyroid carcinoma: Their incidence is only one to two percent. They are very aggressive, spread rapidly and are therefore considered particularly malignant.
• Medullary thyroid carcinoma: This accounts for up to eight percent of all thyroid carcinomas. This form usually develops spontaneously from the C-cells, but in some cases it can be genetically determined.

Thyroid cancer: causes and risk factors

Researchers have not yet been able to find out exactly why thyroid cancer develops. It is certain that radiation to the head/neck area and ionizing radiation are risk factors for papillary thyroid carcinoma and that there is also a familial component. However, most papillary thyroid carcinomas occur spontaneously.

There is also a link between familial exposure and medullary thyroid carcinoma. However, this only applies to five percent of people suffering from this form of thyroid cancer. You may have what is known as MEN syndrome II. This is a defect on chromosome 11, which is associated with the tendency of some endocrine glands to form tumors. If medullary thyroid carcinoma is diagnosed in a family, relatives should therefore have themselves tested for this genetic defect as a precaution.

Thyroid cancer and radiation

The most important risk factor for thyroid cancer is ionizing radiation, such as that released during a nuclear power plant disaster. There is no doubt that the number of thyroid cancers in children exposed to radiation after a nuclear accident is increasing. Medical radiotherapy can also stimulate cells of the gland to develop cancer if the thyroid gland was also affected by the radiation.

Symptoms: Feeling of pressure in the throat and difficulty swallowing

Initially, when the tumor is still small, there are hardly any signs. Symptoms may occur as the gland grows, which can be explained by its location on the trachea and esophagus. This is because cancer can cause pressure on these organs as it grows. Pressure or infiltration-related damage to the vocal cord nerves also occurs in rare cases. The most common symptoms are therefore

• Your throat feels constricted and you have difficulty swallowing.
• They find it harder to breathe and suffer from shortness of breath as a result of exertion.
• Rarely persistent hoarseness
• A lump can be felt in the thyroid gland.
• Cervical lymph nodes may be swollen.

Unfortunately, these symptoms are very unspecific and can also occur with a benign enlargement of the thyroid gland.

Thyroid cancer: Diagnosis with us

You should have each of these symptoms checked by your doctor. After taking a detailed medical history and asking whether you have a family history of thyroid cancer, we will first examine you manually, i.e. palpate the thyroid gland and the cervical lymph nodes.

Several examination methods are suitable for clearing up or, on the contrary, confirming the suspicion and finding out more details about the thyroid cancer:

• Ultrasound examination (sonography): It can provide initial indications as to whether a lump is benign or malignant, or whether it is a harmless cyst, for example.
• Blood test: It shows how well the thyroid gland is working; the so-called TSH value is measured as a very sensitive test.

Thyroid scintigraphy and thyroid puncture for suspected thyroid cancer

If the blood test reveals a suspected hyperthyroidism, a scintigraphy can be used for further clarification. The latter can provide information on whether there are areas in the thyroid gland that have taken on a life of their own and no longer listen to the signals from the brain. In healthy people, the brain releases hormones (TSH) to ensure that thyroid hormone production meets the body’s needs.

Puncture of the suspicious nodes

If the blood test (TSH value) is unremarkable, the ultrasound examination decides whether a puncture of the suspected cancerous nodule is advisable. We use a fine needle to remove cells from the lump, which are then carefully examined under a microscope. In most cases, a thyroid puncture provides certainty.

If the result is positive, it is a thyroid carcinoma, if it is negative, it is a benign lump and an ultrasound check can be planned. Sometimes, however, no diagnosis can be made by fine needle aspiration. In the case of follicular neoplasms in particular, it is not possible to decide whether the tumor is benign or malignant. If in doubt, we recommend removing the knot. Subsequent examination of the entire nodule (histology) allows malignancy to be reliably distinguished from benignity.

If the examinations and tests show that there is a high probability of thyroid cancer, the results are discussed at our interdisciplinary tumor board. The extent of the operation is determined here. Once the definitive histology is available, the Board also decides on the next therapeutic steps.

Thyroid cancer: prevention, early detection, prognosis

There are no specific preventive measures to help avoid thyroid cancer. There are also no specific behaviors to prevent benign lumps other than abstaining from nicotine. In Switzerland, the iodine supply is guaranteed via table salt. This prevents growth of the thyroid gland caused by iodine deficiency.

At the slightest suspicion, take the opportunity to detect a developing tumor as early as possible. Ultrasound and/or palpation provide the first suspicious facts. A simple blood test can be used to check how the thyroid gland is working.

If you have a family history of thyroid cancer, please have yourself tested for medullary thyroid carcinoma and for the corresponding genetic mutation. If this suspicion is confirmed, the entire family should be tested for this genetic defect.

And important for anyone who had to undergo radiotherapy as a child or adolescent: please have your thyroid checked regularly to see if it has changed.

Progression and prognosis of thyroid cancer

The decisive factor is at what stage the thyroid cancer was discovered and what form it is.

• Most favorable prognosis: The prognosis for papillary thyroid carcinoma is particularly positive. Almost 90 percent of those affected are cured. Similarly good cure rates are achieved with follicular carcinoma.
• Good prognosis: Up to 70 percent of patients with medullary thyroid carcinoma also remain tumor-free for the first ten years. If the carcinoma is detected very early and treatment is started at the onset of the disease, the chances of recovery are as high as 90 percent, comparable to those for papillary thyroid carcinoma.
• Less favorable prognosis: Undifferentiated thyroid carcinomas are often problematic because they often cannot be completely removed surgically. The survival rate after five years is twelve percent. Some of these tumors may also give rise to offshoots. However, increasingly effective therapies are making it possible to control the disease even at an advanced stage.

Self-help groups

The exchange with people who are affected by the same disease can be a great support in coping with the disease. Advice on finding a suitable self-help group is available from Selbsthilfe Zürich. Self-Help Zurich and the University Hospital Zurich are cooperation partners in the national project “Health literacy thanks to self-help-friendly hospitals”.

Thyroid cancer: treatment with surgery and radioiodine therapy

If thyroid cancer is suspected on the basis of the fine needle aspiration, surgery is the first step. Whether only half or the entire thyroid gland needs to be removed depends on factors such as the size of the findings and indications of particularly aggressive growth in the fine needle aspiration. It may also be necessary to puncture and remove any abnormal lymph nodes in the neck that are detected by ultrasound. In some cases, no further measures are necessary apart from the operation and aftercare begins with sonographic and laboratory checks. For thyroid carcinomas with an increased risk, it may be necessary to administer radioiodine after the operation.

Overall, it is becoming apparent that thyroid cancer treatment is planned and carried out on an individual basis. If the tumor is smaller than one centimeter (microcarcinoma), in some cases the tumor cannot be treated at first, but can be monitored closely, for example with ultrasound.