Thyroid Cancer

The thyroid is a butterfly shaped gland located in the lower neck, just below your voice box (larynx). It produces two thyroid hormones, thyroxine (T4) and triiodothyronine (T3). These hormones regulate how the body uses energy (controls your metabolism).

Thyroid cancer occurs as an abnormal growth (nodule) in the thyroid gland. Although, most nodules are benign, some develop cancer that can spread throughout the body and be life threatening. Most patients with thyroid cancer will have no symptoms. The cause of thyroid cancer is not known, but you may be at risk for developing thyroid cancer if you have risk factors. Some of these risk factors include radiation treatments to the head, neck, or chest, (not routine chest or dental x-rays), if you have a family history of thyroid cancer or a large or rapidly growing nodule. Most people with thyroid cancer do not have these risk factors which is why all nodules should be investigated thoroughly. Diagnosis requires cytologic (fine-needle biopsy) or histologic (surgical pathology) confirmation.

There are 4 types of thyroid cancer:

1) Papillary Thyroid Cancer (PTC) is the most common type and accounts for >85% of thyroid cancer is South Texas. PTC typically grows slowly and often spreads to the lymph nodes in the neck. Spreading to the lungs or bones can also occur. If diagnosed and treated when <1cm, most patients enjoy surgical cure and need to be followed on thyroid hormone replacement for life. Survival can be greater than 95% over 20 years. Do Patients with Low- and Intermediate-Risk Thyroid Cancer Need Continuing Postoperative Neck Surveillance Ultrasounds?

2) Follicular Thyroid Cancer (FTC) is the second most common type (about 10% of cases). It rarely spreads to the lymph nodes but will more commonly spread to the lungs or bones. If diagnosed and treated when <1cm, overall cure rate is still >90%.

3) Medullary Thyroid Cancer (MTC) is associated with genetic disorders called MEN syndromes (Multiple Endocrine Neoplasia) where other endocrine tumors and malignancies exist. It is a rare form of thyroid cancer causing <5% of cases. If found very early before spread, there is a 90% chance of 10 year survival. However, more commonly, patients tend to have persistent disease with recurrences in lymph nodes owing to a 70% survival over 10 years. This drops to less then 20% survival if spread to distant site. Because of it’s genetic predilection, this thyroid cancer can run in families and requires careful family member evaluation to determine if they are at risk and may even require a prophylactic thyroidectomy (surgical removal of thyroid even thought there is no obvious tumor).

4) Anaplastic Thyroid Cancer (ATC) is the least common form, owing to <1% of all thyroid cancers and is very aggressive usually affecting those over 65 years old. It progresses despite chemotherapy, radiation therapy and surgery. Research at MD Anderson in Houston, TX has shown some promise with experimental agents which may slow the progression of this cancer. Anaplastic and Medullary cancers in later stages are candidates for these cancer protocol programs.
Treatment of thyroid cancer depends on the size of the cancer, the type and extent of spread, as well as your age.
The primary treatment is surgical removal as well as possible removal of nearby lymph nodes. Risk of hypoparathyroidism (causing low calcium) and recurrent laryngeal nerve injury (damage to the nerve to the vocal cord causing hoarseness) occurs < 2% when done by experienced thyroid surgeon.

Sometimes thyroid lobectomy (hemithyroidectomy, removal of ½ gland) is an acceptable surgery for a <1cm possibly malignant thyroid nodule. Micro-PTC defined as cancers < 1cm, without spread beyond the capsule are considered stage I and low risk, and surgical cure is the rule. However, recurrences are not uncommon. Lymph node metastasis (spread) is seen in 40% of patients with PTC. Total lymphadenectomy of involved nodes should be performed. Lymph node metastasis increases the risk of subsequent lymph node recurrence but have little effect on survival.

After surgery, your thyroidologist will determine the proper course for you based on your stage of cancer.
If you think you have thyroid nodules, or have a family member with a thyroid condition, visit an endocrinologist who specializes in thyroid conditions for diagnosis and treatment.

If you are diagnosed with thyroid cancer, you will need proper management BEFORE surgery by an expert in thyroid care and continued monitoring after surgery to ensure proper monitoring of your disease. The plan for you is individualized to you and your type and stage of cancer.

Take medications EXACTLY as prescribed. If you do not take your thyroid medication as instructed, it may not be properly absorbed and you may stimulate your cancer to persist or return. The dose of Thyroid Hormone Suppression: is the dose of levothyroxine hormone (LT4) determined based on your stage of disease to prevent hyperthyroidism and to minimize TSH stimulation of tumor growth. Too much hormone also carries risks (cardiac arrhythmias and osteoporosis) therefore; suppression should be based on staging/aggressiveness of disease and risk of recurrence.

Most recurrence of thyroid cancer occur within the 1st five years after initial treatment but may recur many years later. Therefore, periodic physical exam and regular lab assessment for thyroglobulin (TgAg) on LT4, will alert you to early recurrence. Regular follow-up visits ensure a proper drug level, prevent complications and find recurrences early.

Resources

American Thyroid Association: www.thyroid.org

Thyroid Cancer Survivors’ Association: www.thyca.org

National Cancer Institute: www.nci.nih

Find-an-Endocrinologist: www.hormone.org