Every year, about 2,000 to 3,000 people in Germany develop thyroid cancer – making it one of the rarer malignant tumor diseases. On average, women are affected 3 times more often than men. There are different forms with different prognoses. Since Germany is an iodine deficient area, there are comparatively many people who have an enlarged or nodular thyroid gland – scientists assume 10 percent. In rare cases, a tumor may be hidden behind this, which is initially not paid any attention to. Symptoms usually appear only at an advanced stage.
What forms of cancer are there and who is affected?
- Papillary thyroid carcinoma: 35 to 60% of malignant thyroid tumors; 3 times as many women as men affected; patients usually over age 40. Prognosis good to very good.
- Follicular thyroid carcinoma: 25 to 40% of malignant thyroid tumors, women 3 times more often affected; patients usually between 40 and 50 years old.
- Medullary thyroid carcinoma: Arises from the C cells that produce the hormone calcitonin. Makes up 5 to10% of tumors, women and men are affected about equally. Age of onset is approximately 40 to 50 years. The prognosis is good to moderate.
- Undifferentiated (anaplastic) thyroid carcinoma: The cell type is not determinable in this case. It accounts for about 10% to 20% of thyroid carcinomas. It affects twice as many women; the age of onset is about 50 years. The prognosis is poor because metastases are set very early and the tumor responds poorly to therapy.
- Other: this includes all other forms that may be found in the thyroid gland, for example, cancer of surface cells or metastases from other tumors. The prognosis depends on the underlying disease.
How does thyroid cancer develop?
As with most cancers, the exact causes are still unknown. However, there are some factors that are known to trigger thyroid cancer. One significant one is long-term iodine deficiency – thought to increase the risk of developing thyroid cancer twofold. In particular, follicular carcinoma is more common in people with thyroid enlargement due to iodine deficiency. Hereditary factors, on the other hand, play a role especially in medullary thyroid carcinoma. It is not uncommon for this tumor to be accompanied by hormonal disorders and tumors of other organs. It has long been known that the thyroid gland reacts very sensitively to ionizing radiation. For example, a greatly increased number of thyroid cancers were found in survivors after the respiratory bombing in Hiroshima or in victims after the reactor disaster in Chernobyl.
How does the disease manifest itself?
Often, no symptoms are present for a long time. The first indication is usually the rapid growth of the thyroid gland, and nodules may be palpable. Difficulty swallowing may occur. The adjacent lymph nodes may also be enlarged, leading to pressure, swallowing or neck pain. Later, the vocal nerve may be pinched off, causing hoarseness. If there is a tumor that produces hormones, these can cause symptoms, as in hyperthyroidism.
How is the diagnosis made?
After taking a medical history, the doctor will first palpate the thyroid gland and surrounding lymph nodes. An important examination is ultrasound. This can detect the size of the thyroid gland, nodules, cysts, and other tissue changes. Scintigraphy can be used to visualize the function of the thyroid gland using radioactively labeled contrast medium. Malignant nodules are usually “cold,” meaning that they do not produce hormones, unlike normal tissue. With a targeted puncture, cell material can be taken from suspicious areas with a fine needle and evaluated under the microscope. If the suspicion of a tumor is confirmed, computer tomography and bone scintigraphy are used to detect metastases from daughter tumors. In addition, blood is taken and tested for hormones and other substances. For certain tumors, family screening is performed to determine hereditary predisposition.
What therapy is available?
The main treatment is usually complete removal of the thyroid gland and adjacent lymph nodes.About 4 weeks after the operation, radioiodine therapy follows in order to destroy metastases or remaining tissue remnants. For this purpose, radioactive iodine is swallowed in a capsule, which accumulates in the relevant tissue, irradiates it locally and thus destroys it. This treatment may have to be repeated. Radiation therapy may also be administered externally. Subsequently, the affected person must take thyroid hormones as tablets for life and undergo semi-annual, then annual check-ups for 10 years.
