Endocrine System Cancers

Endocrine System Cancers

Reviewed By:
Martin E. Liebling, M.D., FACP

Summary

Endocrine system cancers are malignant tumors that occur in the glands responsible for producing and secreting hormones. Hormones are chemical messengers that coordinate activities throughout the body. Except for thyroid cancer and cancer of the gonads (ovaries in females and testes in males), endocrine system cancers are rare disorders and are usually treatable when caught early.

The glands of the endocrine system exist in many parts of the body and control many functions, such as growth, metabolism, digestion and blood pressure. Endocrine glands include the pituitary gland and hypothalamus in the brain, the thyroid and parathyroid glands in the neck and the adrenal glands over the kidneys. Certain cells in the pancreas may also develop endocrine cancers. Thyroid cancer is the most common non-reproductive organ endocrine cancer. The remaining endocrine cancers are quite rare.

Endocrine system cancers usually cause an endocrine gland to produce too little or too much of a hormone. The changes in these hormone levels may produce symptoms such as weight changes, fatigue or vision changes. The cause of most endocrine system cancers remains unknown. Even though there are some associated risk factors, most people who develop an endocrine cancer have no known risk factors.

The reproductive glands of the ovaries in women and testes in men may also develop cancer. These cancers are more common than othre types of endocrine system cancer.

About endocrine system cancers

Endocrine system cancers are malignant growths in the glands that produce and secrete hormones, the substances that help coordinate activities throughout the body. Cancers rarely occur in most endocrine glands,  except for the reproductive glands (ovaries in females and testes in males). Endocrine cancers are usually treatable when caught in their early stages. Most tumors that develop in the endocrine glands are benign (noncancerous).

The glands of the endocrine system produce hormones and secrete them into the bloodstream. Hormones are chemical messengers that regulate many body functions, including growth, development, metabolism and how the body uses other chemicals. Cancer can affect all the endocrine glands. These include the pituitary gland and hypothalamus in the brain, the thyroid and parathyroid glands in the neck, the adrenal glands above the kidneys and the endocrine cells of the pancreas. The testes in men and ovaries in women are also endocrine glands.

Other than in the reproductive organs, endocrine system cancers are relatively rare. The most common form outside the reproductive organs is thyroid cancer.

All diseases of the endocrine system, including cancer, can be difficult to diagnose. Conditions that affect the hormones may produce varying symptoms or sometimes no symptoms. Endocrine system cancers usually cause the major organs of the endocrine system to produce too little or too much of a specific hormone, which can trigger various symptoms. When this happens, it is known as a functioning tumor, if it overproduces or continues to produce specific hormones. Other cancers that do not produce hormones are known as nonfunctioning tumors.

 The American Cancer Society estimates that there were 32,260 cases of non-reproductive organ endocrine cancers in 2006. More than 30,000 of those were thyroid cancers, with the remaining cases occurring in the other endocrine glands.

The ovaries in women and the testicles in men are also part of the endocrine system. Cancers in these glands are more common than in other parts of the endocrine system.

Types and differences of endocrine cancers

Endocrine cancers differ depending on where tumors develop. Thyroid cancer is the most common of the non-gonadal endocrine system cancers. Although thyroid cancer is the most common, it accounts for only about 1 percent of all invasive cancers.

Thyroid tumors typically appear as one or more solid or fluid-filled nodules that are usually noncancerous (benign). A small percentage of these nodules are malignant and can cause symptoms such as a lump in the throat just below the Adam’s apple, hoarseness and swallowing difficulties. Several types of cancer can form in the different types of thyroid cells. Most types are treatable and have high survival rates.

Other forms of endocrine cancers include:

  • Islet cell cancer. A rare form of cancer that causes islet cells of the pancreas to make excessive amounts of hormones. Few pancreatic cancers start in the endocrine pancreas, according to the National Cancer Institute. The great majority begin in the exocrine pancreas, which produces digestive juices that help break down food. Tumors found in islet cell cancers may produce excess quantities of hormones such as gastrin, insulin or glucagon. Insulin and glucagon affect the levels of sugar in the blood. Gastrin affects the levels of stomach acid. 
  • Pituitary cancer. Tumor in the pituitary gland that is the result of excessive production of hormones, which can lead to other problems in the body. These tumors may put pressure on the optic nerves and cause vision problems if not treated. In some cases, pituitary tumors can cause Cushing’s disease, in which excessive levels of the glucocorticoid hormones are released into the bloodstream. This causes fat to build up in the face, back and chest, while causing the arms and legs to become very thin. Pituitary tumors can also cause acromegaly, which is an enlargement of the hands, feet and face. Types of pituitary tumors include:
    • ACTH-producing tumor. Produces too much adrenocorticotropic hormone (ACTH), which stimulates the adrenal glands to make glucocorticoids. Too much ACTH can cause Cushing’s disease.
    • Prolactin-producing tumor. Prolactin is the hormone that stimulates a woman’s breasts to make milk during and after pregnancy. In women, these tumors can cause breast-milk production and halt the menstrual cycle when a woman is not pregnant and can also increase the risk of breast cancer.  In men, they can cause impotence.
    • Growth hormone-producing tumor. Produces excessive growth hormone, which causes acromegaly (enlargement of the bones of the face, jaw and extremities) or gigantism (excessive growth of the body or any of its parts).
  • Parathyroid cancer. Problems with the parathyroid glands usually occur when the glands make too much parathyroid hormone, a condition known as hyperparathyroidism. This creates excessive calcium in the blood and drains the bones of calcium, causing symptoms such as pain in the bones and kidney problems. Usually, hyperparathyroidism is the result of a noncancerous condition but in rare cases, it is caused by a cancerous tumor. An inherited disorder called familial isolated hyperparathyroidism and a disorder of the endocrine glands called multiple endocrine neoplasia 1 have both been associated with increased risk of parathyroid cancer.
  • Adrenal tumors. A benign tumor called cortical adenoma may develop in up to 8 percent of people, often with no symptoms or complications. Other types include:
    • Adrenocortical carcinoma. Extremely rare cancer of the adrenal cortex (outer part of the adrenal gland) that causes cells to make too much of one or more hormones, leading to high blood pressure, weakening of the bones and diabetes. In cases where sex hormones are affected, the patient may experience deepening of the voice, excessive facial hair, swelling of the breasts or swelling of the sex organs.
    • Pheochromocytoma. Rare tumors of the adrenal medulla (inner part of the gland). Pheochromocytomas are usually benign but often make the adrenal glands produce excess catecholamine hormones, leading to high blood pressure.
  • Cancer of the hypothalamus. Brain tumors may affect this gland. Because of the deep location of the cancer, radiation therapy may be used rather than surgery.

Cancers that affect the gonads and the kidneys, which also produce hormones, are addressed in separate patient guides.

Risk factors and causes of endocrine cancers

With the exception of thyroid cancer, the cause of most endocrine system cancers remains unknown. There are no known risk factors,  although age, history of smoking, exposure to radiation and other known cancer triggers may raise the risk of cancers of the endocrine system. In women, a family history of ovarian cancer is also a risk factor.

More is known about the risk factors of thyroid cancer than other endocrine cancers. Risk factors include:

  • Goiter
  • Family history of thyroid disease
  • Certain hereditary genetic mutations
  • History of radiation exposure to the neck
  • Diet low in iodine
  • Gender (being female)
  • Age (25 to 65)
  • Race (being Asian or white).

Signs and symptoms of endocrine cancers

Each endocrine cancer has its own characteristic symptoms based on its location and the type of hormone it produces. The general indicators attributed to endocrine system cancers may include:

  • Abdominal pain

  • Digestive problems, including nausea, diarrhea and vomiting

  • Fatigue and weakness

  • Unexplained weight changes:
    • Weight gain may be due to adrenal carcinoma
    • Weight loss may be due to pituitary, parathyroid or pancreatic cancer (also to hormone therapy)

  • Headaches

  • Vision impairment (for pituitary cancer)

  • Difficulty breathing and swallowing (for thyroid cancer)

  • Bone pain and fractures (for parathyroid cancer)

  • High blood pressure (for adrenal cancers), evidenced by rapid hearbeat, anxiety or sweating.

  • Hypoglycemic episodes (for islet cell tumors)

Diagnosis methods for endocrine cancers

To diagnose endocrine system cancers, a physician will first obtain the patient’s medical history and conduct a physical examination. There are many methods of testing for endocrine system cancers. Different methods are used for different types of cancer. The most commonly used methods include:

  • Blood tests and urine tests. These are often used to detect higher levels of hormones in the blood. For example, a physician who suspects the type of thyroid cancer known as medullary cancer might order a blood test to look for high levels of calcitonin, the hormone that regulates the amount of calcium in the blood.
  • Fine-needle aspiration biopsy. A needle is inserted into suspected tissue and a sample of cells is removed. The cells are then analyzed to determine if the cells are noncancerous (benign) or cancerous (malignant). If this test proves inconclusive, a surgical biopsy may be performed in which an entire mass is removed and sent to a laboratory for analysis.
  • MRI (magnetic resonance imaging). Produces clear cross-sectional or three–dimensional images of the body’s tissues, even through bone and other obstructions.
  • CAT scan (computed axial tomography). Uses multiple x-ray images, taken from different angles, to create three-dimensional images of body structures. CAT scan may be used to detect the presence of tumors in tissues and organs in the body.
  • Ultrasound. Sends and receives high-frequency sound waves to create images of internal organs or tissues.
  • PET scan (positron emission tomography). Test in which a small amount of a glucose substance with radioactive tracer is injected into a patient’s vein. A special machine detects and records the energy given off by the tracer substance. Areas that absorb the substance appear as hot spots on the images and can indicate the presence of cancer. This test is often used to determine if and where the cancer has spread in the body.

Treatment and prevention of endocrine cancers

The method of treatment for endocrine system cancers will depend on the type of cancer and its progression. The stage of the cancer will determine whether a cancer is contained, if it has spread, and how far it is has spread. Common therapies used to treat cancer include:

  • Surgery. Used for the complete or partial removal of a tumor or the gland with a tumor. For example, a parathyroid gland or adrenal gland may be removed. In other cases, just the tumor is removed. After removal, medications may be needed to adjust to any loss of the gland’s hormone-production function.
  • Chemotherapy. Uses one or more powerful drugs to target dividing cancer cells to destroy them and to help prevent them from reproducing and spreading throughout the body.
  • Radiation therapy. Uses an energy called ionizing radiation to kill cancer cells and shrink tumors. Radiation targets dividing cancer cells and disrupts or destroys their genetic material, preventing the cells from continuing to grow and spread throughout the body.
  • Biological therapy. Repairs, stimulates or enhances the immune system so that it can better recognize and destroy cancer cells. Certain forms of biological therapy can directly attack the cells as well. This therapy can be used to alleviate side effects associated with cancer treatments such as chemotherapy.
  • Hormone therapy. Certain cancers rely on hormones to grow and spread. Patients who undergo this treatment sometimes take medications that reduce the levels of certain hormones, such as estrogen and testosterone, preventing growth of the cancer. In other cases, patients may take drugs that prevent cancer from attaching to hormones that help the disease thrive.

In addition to these treatment options, patients with endocrine cancers may need additional treatment to control the changes or damage caused by abnormal hormone levels caused by the tumors.

Little is known about how to prevent most endocrine cancers. People with an inherited defect in the RET gene that raises the risk of thyroid cancer sometimes have the gland removed in prophylactic (preventive) surgery. The American Cancer Society recommends reducing the general risk of cancer by regular exercise and eating a diet low in animal fats and high in vegetables, fruits and whole grains.

Questions for your doctor

Preparing questions in advance can help patients have more meaningful discussions with their physicians regarding their conditions. Patients may wish to ask their doctor the following questions about endocrine system cancers (ESC):

  1. Am I at a higher risk for any endocrine system cancers?
  2. What type of test will I need to diagnose my cancer?
  3. Which type of endocrine cancer do I have?
  4. Which organs are affected by this cancer?
  5. What stage is my cancer?
  6. What are the best treatment options for my condition?
  7. How likely is this cancer to spread to other areas of my body?
  8. After the cancer is treated, what are the chances that it will return?
  9. What is my prognosis with this cancer?
  10. Are my children at higher risk for developing this cancer?
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