This is Thyroid Cancer Awareness Month. Thyroid cancer is the most common cancer of the glands, but only accounts for about one percent of all cancers. "The thyroid gland is located in the neck, about a fingerbreadth below the larynx or voice box. This can be identified as the 'Adam's apple' in men," says Geeta Lal, MD, an assistant professor and oncology surgeon at UI Hospitals and Clinics.

"One of the most well-known risk factors for the development of thyroid cancer is radiation to the head and neck," Lal says. "By this, we're not referring to routine dental or chest x-rays, but rather to low dose therapeutic radiation. Many years ago, radiation was used to treat a multitude of conditions such as ringworm infection, enlarged thymus glands, enlarged tonsils, acne, and some birthmarks. Radiation is also used in the treatment of certain cancers like Hodgkin's Lymphoma. The risk is maximum 20-30 years after the exposure, but these individuals need lifelong monitoring. Another mechanism of radiation exposure is that resulting from nuclear fallouts such as the one in Chernobyl in 1986."

Lal says a family history of thyroid cancer is also a risk factor, particularly for a type called medullary thyroid cancer. "This can occur in families by itself, or with other tumors of the adrenal and parathyroid glands when it forms part of a syndrome called multiple endocrine neoplasia 2 (or MEN2). This syndrome results from a mutation or abnormality in the RET proto-oncogene. We can screen for this inherited mutation by genetic testing and offer surgery early to at-risk individuals in these families. We are now also recognizing that the more common types of thyroid cancer (i.e. papillary and follicular cancer) can also have an inherited predisposition."

There are no specific steps people can take to prevent thyroid cancer, Lal says. "However, if you have a thyroid lump(s) or nodule(s), please ensure to have it evaluated.   Even if biopsy results are benign, it is important to follow up with your doctor to make sure that the nodule(s) are not increasing in size as biopsies can be erroneously benign about 2-3 percent of the time.

"Most thyroid cancers we see nowadays are asymptomatic," Lal says. "Some are actually picked up when people have an ultrasound or CT scan for other reasons. Otherwise, a person or their physician may note a lump or nodule in the neck. Symptoms such as a change of voice or difficulty swallowing or breathing may also occur and are usually associated with advanced disease."  

In discussing how thyroid cancer is diagnosed, Lal says, "Approximately 4 percent of the population has thyroid nodules, whereas thyroid cancer incidence is 40 cases per 1 million. That is to say, most thyroid nodules are not cancer (they are benign). So it is important to figure out which nodules are cancerous. Your doctor will check thyroid function with a blood test. Symptoms and physical exam are helpful too. However, the single most useful test is a fine-needle aspiration biopsy, which can be performed with or without ultrasound guidance. Nodules can be classified as benign, cancerous, or suspicious based on the biopsies. False-positive results occur in 1 percent. It is important to remember that the biopsies can be falsely negative about 2-3 percent of the time."    

Lal says there are several "arms of treatment" for the disease that depend on the extent of cancer and the type of thyroid cancer. "Here at UI Hospitals and Clinics, we utilize a multidisciplinary approach to thyroid cancer treatment and patients will have several individuals involved in their care, including surgeons, endocrinologists, nuclear medicine experts, and, rarely, radiation and medical oncologists.

"Generally, the first step is surgery/thyroidectomy, which may involve removal of a part or the whole thyroid gland, in addition to lymph nodes in the neck," Lal says. "This may or may not be followed by radioactive iodine treatment. Patients also need to take thyroid hormone as prescribed by their doctors. Radiation and chemotherapy are rarely used in the treatment of thyroid cancers, except for certain types of aggressive tumors."

Are there side effects of thyroid cancer treatment? Lal says there are risks associated with any surgery, though certain risks are unique to thyroid surgery. "Injury to the recurrent laryngeal nerve leads to hoarseness and difficulty swallowing. Injury to the parathyroid glands, which regulate the body's calcium levels, can lead to hypoparathyroidism, which requires lifelong intake of calcium and vitamin D supplements. Radioactive iodine treatment has its own side effects, the most common being inflammation of the salivary glands, neck pain and tenderness, and nausea or vomiting. Very high doses can affect fertility and cause bone marrow suppression over the long term."

The long-term prognosis for thyroid cancer patients depends on the specific type of thyroid tumor and the stage, Lal says. "The stage takes into account the size of the tumor and its extent (whether it has grown into surrounding structures or lymph nodes or has spread to other parts of the body). In general, patients with papillary thyroid cancer have an excellent prognosis, with greater than 95 percent 10-year survival rates. Follicular and Hurthle cell cancers also have a good prognosis rate, with greater than 85 percent and 80 percent survival at 10 years. Medullary thyroid cancers fare slightly worse, with survival rates of 45 to 80 percent, depending on the stage. Anaplastic cancers are rare (1 percent of all cancers) but have the worst prognosis, with few patients surviving six months beyond diagnosis."

Researchers at UI Hospitals and Clinics are collecting families with papillary and other cancers of follicular cell origin to study the hereditary basis of this malignancy, Lal says. "We are also studying genes that can be used as diagnostic and prognostic markers for thyroid cancer."

Lal suggests the following Web sites for more information: (American Thyroid Association) and (the National Comprehensive Cancer Network).

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