Thyroid Cancer

Most common types of thyroid cancer are “sporadic” or isolated, and not inherited.

• Most common types of thyroid cancer are “sporadic” or isolated, and not inherited. However, an uncommon type of thyroid cancer, medullary, which makes up about 5% of all thyroid cancers, can be familial, or run in families. When medullary cancer is inherited as a familial disease, it can be detected by a genetic blood test. Unless the disease is inherited, your children will not be affected.
• Papillary thyroid cancer is the most common type of thyroid cancer, accounting for 70-80% of call cases. It is most commonly diagnosed in women 30-40 years old and most frequently spreads to cervical (neck) lymph nodes.
• Follicular thyroid cancer is the second most common type of thyroid cancer, accounting for 10-15% of cases. Although it usually does not spread, when it does it goes to the lungs and bones through the bloodstream.
• Anaplastic thyroid cancer accounts for less than 5% of thyroid cancer patients. It is the most aggressive form of thyroid cancer and treatment is rarely effective.

Because the most common thyroid cancers, papillary and follicular, tend to grow slowly, usually do not spread beyond the neck, and respond to treatment, most patients with thyroid cancers have excellent prognoses. For example, the 20-year survival of the most common type, papillary thyroid cancer, is almost 95%.

The estimated number of new thyroid cancer patients for 2011 was 48,020 (incidence rate). This number is due to a continuing upward trend in the number of newly diagnosed thyroid cancer patients of 2% each year for more than 15 years! This represents an alarming and rapid percentage increase for any form of cancer, especially since most all other cancers are either stable or declining in their incidence rates. Fortunately, virtually the entire rate of increasing thyroid cancer patients annually is due to newly diagnosed papillary cancer (rather than other types of more aggressive thyroid cancer). The exact cause (or causes) is not clear; but, this rise in the incidence of papillary thyroid cancer has been attributed to better and earlier diagnostic imaging with ultrasound. However, other background environmental causes are difficult to exclude and there are continuing efforts to analyze this incidence trend.

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As with many types of cancer, the specific reason for developing thyroid cancer remains a mystery in the vast majority of patients. Some major risk factors are:

• External radiation to the head or neck, especially during childhood
• Genetic predisposition (the influence of heredity), particularly for the medullary type of thyroid cancer

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First, your physician takes a detailed history and performs a careful physical examination, especially of the thyroid gland. The best diagnostic approach for a specific patient will be determined by your physician after careful consideration of all the facts. The tests available to your physician for evaluation of the thyroid lump include, but are not limited to, the following:

• Fine-needle aspiration biopsy– this is usually done first and, if positive, significantly reduces the need for more elaborate and expensive testing
• Ultrasonography – this may be required for guidance of the fine needle biopsy if the nodule is difficult to feel
• Thyroid scan – this can be done to see if the mass is capable of concentrating radioiodine, particularly in those patients with low TSH levels, who are likely to have hot nodules, which are almost always benign.
• Blood studies

Read more about these procedures in the Thyroid Nodules section.
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The great majority of patients with thyroid cancer have a disease that can be successfully treated. In order to ensure your chances for successful treatment, it is important to receive treatment and follow-up care from those with a great deal of experience in the diagnosis and treatment of thyroid cancer. This is usually an endocrinologist, a doctor who specializes in hormone-related disorders.

If the diagnosis of thyroid cancer is certain or highly likely, the usual approach is to remove both sides of the thyroid gland. If the diagnosis of thyroid cancer is much less certain or cannot be made during surgery, only the side of the thyroid containing the lump may be removed. If cancer is subsequently confirmed, further consultation with the endocrinologist is appropriate. Additional surgery to remove the remaining tissue and radioactive iodine treatment are usually recommended in order to destroy any remaining malignant thyroid cells and to reduce the risk of recurrence of this disease.

You may be thinking, shouldn’t I be seeing an oncologist. The answer is not usually. The endocrinologist is the physician who deals primarily with the diagnosis, treatment, and follow-up of most patients with thyroid cancer. When standard therapy fails to control the progression of thyroid cancer and chemotherapy is being considered, then consultation with an oncologist is appropriate.
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What treatment will I require?
Treatment depends on the type and extent of cancer. Treatment options include surgery, radioactive iodine, external radiation (see below), and chemotherapy. All patients require thyroid surgery and many receive radioiodine after surgery. External radiation is sometimes necessary when tumors cannot be removed surgically or eliminated by radioactive iodine.

What kind of surgery?
Removal of part or all of the thyroid gland (thyroidectomy) is the first step in management. Lymph nodes with cancer in them are also removed. A surgeon who has experience with thyroid cancer is the best choice for performing your surgery.

Will I require radiation? What type?
Conventional radiation therapy, the type that is generally used for cancer is not used very often to treat thyroid cancer. It is reserved to treat thyroid cancer that cannot be removed surgically or eliminated with radioactive iodine. Fortunately, it is only required to treat a small minority of thyroid cancer cases. This type of radiation treatment is often referred to as external radiation therapy because the source of the radiation comes from outside the body.
Most often patients with thyroid cancer who require radiation treatment receive radioactive iodine. This type of radiation works internally once it enters your body. It is administered by either swallowing a capsule or drinking a radioactive liquid; containing a radioactive form of iodine.

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Radioactive iodine treatment should never be given to a pregnant or nursing woman. Small amounts of radioactive iodine will also be excreted in breast milk. Since radioiodine could permanently damage the infant’s thyroid, breast-feeding is not allowed. If radioiodine is inadvertently administered to a woman who is subsequently discovered to be pregnant, the advisability of terminating the pregnancy should be discussed with the patient’s obstetrician and endocrinologist. Therefore, prior to administering diagnostic or therapeutic radioiodine treatment, pregnancy testing is mandatory whenever pregnancy is possible.

After radioiodine therapy, thyroid medication (levothyroxine) should be started and dosed to replace the function of the thyroid and to decrease the likelihood of cancer recurrence. Periodic monitoring is supervised by the endocrinologist, and may include ultrasound examinations, radioiodine body scans, and periodic testing of a blood protein called thyroglobulin, which is found in normal thyroid cells but can also be produced by thyroid cancer cells.

The optimal frequency of further monitoring studies to be certain that the cancer has not recurred will be determined by your physician. Fortunately, most cases of thyroid cancer have a very good prognosis when diagnosed early and treated by a physician who is familiar with its management.
Learn more and pregnancy and thyroid here.

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