Thyroid Nodules  
     
Thyroid nodules are abnormal growths or lumps that form in the thyroid, a butterfly-shaped gland that releases important hormones used for metabolism and the body’s growth and development. The thyroid is located at the front of the neck below the larynx and in front of the windpipe.

A thyroid lump may be solid or fluid-filled, and is often detected via routine medical exams and imaging tests like X-rays and CT scans. These nodules are generally harmless, with 95% of all cases being benign.
Causes and Symptoms

Though common, the exact cause of thyroid nodules is unknown. However, in most cases, the occurrence of these lumps is usually attributed to:
  • Iodine Deficiency - A diet lacking in iodine leads to low production of thyroid hormones, which then results in an enlarged thyroid and the formation of nodules.
  • Overgrowth of Normal Thyroid Tissue - Though known as thyroid adenomas, these overgrowths are benign and harmless.
  • Thyroiditis - This is a general term referring to the chronic inflammation of the thyroid. One form of thyroiditis called Hashimoto’s disease, which results in an underactive thyroid gland leading to nodules and hypothyroidism.
  • Thyroid Cysts - These are usually a result of degenerating thyroid adenomas. These cysts are mostly benign.
  • Goiter - This is the abnormal enlargement of the thyroid caused by iodine deficiency and an over- or underproduction of thyroid hormones.
  • Thyroid Cancer - This condition occurs when abnormal cells or tumors develop in the thyroid. It is one of the most curable cancers when detected early.
Most thyroid nodules are asymptomatic, producing no symptoms unless they are large enough to protrude and be seen or felt on the neck or throat. Other symptoms include:
  • Enlarged thyroid gland
  • Hoarse voice
  • Breathing and swallowing difficulties
  • Pain at the base of the neck
  • Swollen lymph nodes
  • Choking sensation, especially when lying down
  • Tickling feeling in the throat
In some cases where the thyroid lump is causing the over- or underproduction of thyroid hormones, symptoms of hyper- or hypothyroidism will show up. These include:
  • Arrhythmia (irregular heart rhythm)
  • Unexplained weight gain or loss
  • Muscle cramps and weakness
  • Persistent fatigue
  • Difficulty sleeping
  • Dry hair and skin
Thyroid Cancer

Thyroid cancer develops when thyroid cells become mutated and begin growing, eventually forming a tumor within the gland. Left untreated, the cancer may spread to the nearby lymph nodes, lungs, bone, and in some cases, even the brain.

However, if detected early, thyroid cancer is one of the most curable cancers with a 5-year survival rate of 98%. At its earliest stages, the cancer may be completely eradicated via surgery.
Thyroid Cancer Symptoms

Similar to nodules, thyroid cancer does not present any symptoms during its early stages, but as the tumors grow, they may cause:
  • A palpable lump on the neck or throat
  • Pain in the neck and throat
  • Swollen lymph nodes
  • Breathing and swallowing difficulties
  • Hoarse voice
Some forms of thyroid cancer may also manifest symptoms such as facial flushing, lethargy and severe diarrhea.

Having one or most of these symptoms doesn’t always point to cancer. Doctors will need to conduct additional testing to rule out other conditions such as nodules, cysts and other thyroid problems.
Types of Thyroid Cancer

Thyroid cancer comes in several types, which are:
  • Papillary Thyroid Cancer - The most common variation of thyroid cancer, accounting for about 80% of all cases, papillary thyroid cancer begins in the follicular cells where thyroid hormones are produced and stored. Tumors are slow-growing, but can affect one or both lobes of the thyroid, as well as spread to nearby lymph nodes. It occurs more frequently in patients between 30 to 50 years old.
  • Follicular Thyroid Cancer - About 1 in 10 cases of thyroid cancer is attributed to follicular carcinoma, which also develops from the follicular cells, but is more common in patients aged 50 and above. It is more likely to spread to the bones and the lungs if left untreated. Iodine deficiency is seen as a probable cause of this cancer.
  • Medullary Thyroid Cancer - This rare form of cancer begins in the thyroid C cells, which produces calcitonin, a hormone that helps regulate phosphate and calcium levels in the blood. It can affect both children and adults.
  • Anaplastic Thyroid Cancer - Accounting for less than 2% of thyroid cancer cases, this type is very rare, but it is also quite aggressive, quickly spreading to other tissues and organs. It commonly affects older adults aged 60 and above.
  • Thyroid Lymphoma - This is a rare variation of thyroid cancer which develops from the immune systems cells within the gland. It is also aggressive and frequently afflicts those who are 60 years old and up.
Thyroid Cancer Treatment

Treatment for thyroid cancer cases depend on its type and stage. Surgery is usually the first-line treatment to early-stage thyroid tumors. Depending on the size and location of the tumor, part (lobectomy) or all (thyroidectomy) of the thyroid gland may be removed. If the cancer has spread to nearby lymph nodes, these will also be extracted.

Following surgery, radioactive iodine ablation (RAI) is advised to completely eradicate the cancer and prevent recurrence. RAI is available in capsule or liquid form, and is prescribed to target and destroy remaining cancerous thyroid cells without affecting surrounding tissues and organs.

Thyroid hormone therapy, meanwhile, reduced the thyroid-stimulating hormone (TSH) levels in the body, preventing cancerous thyroid cells from growing or recurring. It may also be prescribed after lobectomy or thyroidectomy.

For advanced forms of thyroid cancer, chemotherapy, and targeted and X-ray therapies are recommended.

Prof Christopher Goh is an ENT, head and neck surgeon in Singapore who has over 20 years of experience in treating benign and malignant tumors in the thyroid and salivary glands, throat, voice box and more. To learn more about our services, call 9754-4719.
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