Thyroid cancer

Thyroid cancer is a type of malignant growth that occurs within the thyroid gland, a butterfly-shaped endocrine gland located at the front of the neck. The primary function of the thyroid gland is to secrete hormones such as thyroxine (T4) and triiodothyronine (T3), which regulate the body's metabolic rate.

Histopathology of papillary thyroid cancer in a thyroglossal cyst, high magnification

Types of Thyroid Cancer

• There are four main types of thyroid cancer:
• Papillary thyroid cancer is the most common type, accounting for about 80% of all thyroid cancer cases. This type typically grows slowly and usually remains confined to the thyroid gland. It may, however, metastasize to lymph nodes in the neck.
• Follicular thyroid cancer accounts for approximately 10-15% of thyroid cancer cases. It can invade blood vessels and spread to distant organs such as the lungs and bones.
• Medullary thyroid cancer represents about 2-3% of thyroid cancer cases. It begins in the parafollicular C cells of the thyroid, which produce the hormone calcitonin. Elevated levels of calcitonin in the blood can indicate medullary thyroid cancer at a very early stage. Some forms of this type are associated with inherited genetic syndomes.
• Anaplastic thyroid cancer is a rare and rapidly growing cancer making up less than 2% of thyroid cancers. It is very aggressive and difficult to treat.

Symptoms and Signs

• Thyroid cancer often does not cause any symptoms early in the disease. As the cancer develops, symptoms can include:
• A lump in the neck, sometimes growing quickly
• Swelling in the neck
• Pain in the front of the neck, possibly extending to the ears
• Changes to the voice, including increasing hoarseness
• Difficulty swallowing or breathing
• Persistent cough

Diagnosis

• Diagnosis of thyroid cancer typically involves a comprehensive medical history, physical examination, blood tests, imaging studies, and ultimately, a biopsy.
• Ultrasound is often used as a first-line imaging tool to evaluate any lumps in the thyroid. Fine-needle aspiration (FNA) biopsy, wherein a thin needle is inserted into the thyroid nodule to collect cells for analysis, is the gold standard for diagnosis. Additionally, blood tests are used to measure levels of thyroid-stimulating hormone (TSH), and in cases of medullary thyroid cancer, calcitonin and carcinoembryonic antigen (CEA) levels are evaluated.
• Genetic testing may also be recommended, particularly in the case of medullary thyroid cancer, which can be associated with certain genetic syndromes, such as Multiple Endocrine Neoplasia type 2 (MEN2).

Treatment

The treatment of thyroid cancer depends on the type and stage of the disease, as well as the patient's overall health. Options include surgery, radioactive iodine treatment, thyroid hormone therapy, external beam radiation therapy, chemotherapy, targeted therapy, and immunotherapy.

Epidemiology and Prognosis

• Thyroid cancer represents about 3% of all new cancer diagnoses in the United States. The incidence rate has been increasing over the past few decades, possibly due to advancements in imaging techniques leading to increased detection.
• The prognosis for thyroid cancer is generally good, particularly for patients under 45 years of age and for those with papillary or follicular thyroid cancer. However, anaplastic and advanced medullary thyroid cancer can be challenging to treat.

See Also

Cancer Radiation therapy Chemotherapy

References

American Cancer Society. (2023). Thyroid Cancer: Overview and Types. Retrieved from https://www.cancer.org/cancer/thyroid-cancer/about/what-is-thyroid-cancer.html National Cancer Institute. (2023). Thyroid Cancer - Patient Version. Retrieved from https://www.cancer.gov/types/thyroid Mayo Clinic. (2023). Thyroid cancer - Symptoms and causes. Retrieved from https://www.mayoclinic.org/diseases-conditions/thyroid-cancer/symptoms-causes/syc-20354161 Cleveland Clinic. (2023). Thyroid Cancer: Diagnosis and Treatment. Retrieved from https://my.clevelandclinic.org/health/diseases/8541-thyroid-cancer American Thyroid Association. (2023). Medullary Thyroid Cancer. Retrieved from https://www.thyroid.org/medullary-thyroid-cancer/

External Links

Thyroid cancer Resources
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Thyroid Cancer Survivors' Association - A non-profit organization for education and support for people affected by thyroid cancer.