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Many thyroid cancer patients are initially unaware that they have the disease. Often, a lump is found on the thyroid during a routine physical exam or while taking an image of their neck for other conditions. In the vast majority of the population, a lump is simply an infection or other benign condition of the thyroid. However, about five percent of the time, the nodule can be cancerous. Every year 20,000 new cases of thyroid cancer are diagnosed in the United States. Women are three times more likely to have thyroid cancer than men. Thyroid cancer is most common after 30, but it can develop at any age.
There are four types of thyroid cancer:
- Papillary Thyroid Carcinoma
- Follicular Thyroid Carcinoma
- Medullary Thyroid Carcinoma
- Anaplastic Thyroid Carcinoma
Most patients do not experience symptoms. However, some may feel enlarged lymph nodes or nodules in the neck or have difficulty swallowing or speaking. Although other conditions can also cause these symptoms, it is best to have a physician examine you.
A combination of symptoms, medical history, physical exams, and tests are used to determine a diagnosis. Thyroid nodules are often found during a routine physical examination. Your doctor might feel an abnormal lump on the front of your neck.
- The TSH blood test measures a pituitary gland hormone that stimulates the thyroid gland. If the TSH level is increased, the thyroid gland may not be functioning properly. Additional blood tests are needed to measure other thyroid hormones. Both pituitary and thyroid tests are required to confirm that the problem is located in the thyroid gland.
- T4 and T3 by RIA are blood tests also used to measure thyroid function.
- A thyroid scan measures the amount of iodine the thyroid can absorb.
- Thyroid ultrasound uses painless sound waves to create an image of the thyroid gland and identify nodules. Ultrasounds can show if a nodule is solid or a fluid-filled cyst, but it cannot determine if a nodule is benign or malignant.
- Fine Needle Aspiration Biopsy (FNA). A needle is placed into the thyroid nodule, the cells are aspirated, and then examined under a microscope to determine if a nodule is cancerous.
The most important treatment for thyroid cancer is to completely remove the tumor along with the remaining thyroid gland (total thyroidectomy). Surgeons at the Thyroid Cancer Program are experts in the treatment of thyroid tumors. Using this type of therapy, the majority of cancers will be either cured or controlled and less than 20 percent will show progression. Most of the time, residual cancer can be treated with additional surgery or radioactive iodine. For resistant tumors, external beam radiation may be prescribed or the patient may be entered into a clinical trial with newer therapies or receive some existing targeted chemotherapies. Fortunately, most patients have an excellent prognosis when treated early by experienced physicians.
Radioactive iodine treatment has been prescribed for over 50 years and is often used to destroy residual thyroid tissue as well as any thyroid cancer that is remaining. It may be administered by swallowing a capsule after an individual has been off their thyroid hormone for a number of weeks (endogenous withdrawal protocol) or following two injections of Thyrogen while the patient remains on thyroid hormone. The patient must be on a low-iodine diet for two weeks before the therapy and are usually hospitalized for two days in isolation in order to avoid environmental contamination with radioactivity. Two days after the radioactive iodine is given, thyroid hormone therapy is resumed if the patient has stopped their thyroid hormone. A full body scan is done at two days and seven days following the therapeutic doses of radioactive iodine in order to detect residual thyroid tissue. Since surgery removes the vast majority of thyroid tissue, much of the radioiodine will not be absorbed and will leave the body primarily through the urine. Small amounts will also be excreted in saliva, sweat, tears, vaginal secretions, and feces. Nearly all the radioactive iodine will leave the body during the first two days after the dose has been given.
Side effects are minimal and typically transient. The most common side effects include decreased taste, nausea, inflammation of the salivary glands or dry eyes. Nuclear medicine staff and your endocrinologist will provide you with more information should this be part of your thyroid cancer treatment.
External Beam Radiation
External beam radiation uses radioactivity from a high energy X-ray machine to destroy cancer cells. Malignant cells receive a high dose of radiation for approximately five minutes, during a six- to eight-week course of treatment. Side effects are fatigue, redness in the treated area, hoarseness or difficulty swallowing
Unlike other cancers, traditional chemotherapy has not been shown to be beneficial in the treatment of thyroid cancer. For thyroid cancers that have become resistant to radioactive iodine or which continue to progress despite surgery and/or external beam radiation, a number of new medications that target the biochemical abnormalities in thyroid cancer are available. Although none of these therapies are currently approved by the Food and Drug Administration for the treatment of thyroid cancer, a number of clinical studies have shown that they are reasonably effective in halting the progression of the tumor. As part of the Southern California Thyroid Cancer Consortium, Cedars-Sinai's Thyroid Cancer Program physicians are well versed in the administration of targeted therapies and are kept abreast of current clinical trials on the west coast.
Following surgery or other treatments, regular follow-up visits with an endocrinologist are very important to check for the return of cancer to the thyroid or the spread of cancer cells to other organs in the body. Monitoring of thyroglobulin levels with periodic blood tests is key to proper treatment. Consistently high levels of thyroglobulin can signal a return of the cancer. Depending on the size of the tumor, the rate of growth or how close it is to other organs, a physician may recommend further imaging diagnostics and treatment. Thyroid cancer can recur as late as 20 or 30 years after the original diagnosis or treatment, although if a patient remains cancer free for five years, the recurrence rate decreases.