The Immune System
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Thyroid cancer is a disease that results from the abnormal growth of cells in the thyroid gland, a butterfly-shaped organ situated at the base of the neck. This type of cancer often appears in a benign form and is relatively rare in malignant forms.
Benign thyroid tumors, also known as benign nodules, are quite common, affecting approximately 25-50% of the population. These nodules usually do not cause significant problems and often go unnoticed. They are sometimes discovered during routine medical examinations or when patients experience symptoms of thyrotoxicosis (an excess of thyroid hormones) or difficulties with speech and swallowing due to the compression of surrounding tissues.
Malignant thyroid nodules, on the other hand, are less common, accounting for less than 10% of cases. These can be classified into several types:
Papillary: This is the most common type of thyroid cancer, accounting for 70-80% of all cases. It often affects younger patients (between 30 and 50 years old) and is characterized by a low degree of malignancy, which tends to increase in older patients.
Follicular: This type represents 5 to 15% of all thyroid cancers and is mostly found among the elderly. It is more aggressive than papillary carcinoma but maintains slow growth and a relatively favorable prognosis.
Medullary: This type accounts for approximately 4-5% of thyroid tumors and develops from the C cells of the thyroid, responsible for the production of the hormone calcitonin. It usually affects people over the age of 50 and can be sporadic or familial (inherited).
Anaplastic: This is a rare type of thyroid carcinoma (approximately 1% of cases), found in elderly people with long-standing voluminous goiter and has a very high degree of malignancy.
Other less common malignant forms include thyroid lymphoma and squamous cell carcinoma.
Thyroid cancer often grows very slowly and is minimally invasive. Consequently, the disease often remains unrecognized for life. The most characteristic symptom is the presence of a nodule in the front region of the neck, corresponding to the anatomical location of the gland. However, only a small percentage of these nodules have malignant characteristics.
In younger patients, the initial symptom may be the enlargement of the lateral cervical lymph nodes. In advanced stages, this symptom may be associated with changes in voice tone (hoarseness - dysphonia), widespread pain in the front region of the neck, and dysphagia (difficulty and pain when swallowing).
Certain factors increase the likelihood of a nodule being malignant. These include:
The incidence of follicular cancer is also higher in areas with iodine deficiency, where nodular goiter is endemic. This can be prevented through the use of iodized salt.