Thyroid cancer is cancer that originates from the thyroid tissue. There are those with a quiet and slow progression, as well as those with a fast and aggressive course. Thyroid cancers originate from thyroid follicular cells or C cells.

The thyroid gland is our largest endocrine organ. It is located in our neck, under the front of the trachea, close to the sternum. It weighs about 25 grams. It secretes T3 and T4 thyroid hormones and calcitonin. It has two symmetrical lobes, the right and left lobes. There are follicles inside the lobes. Follicles are formed by typhoid follicular cells. Thyroid follicular cells are located in the epithelial tissue surrounding these follicles. Inside the follicles, there is a colloid substance filled with iodide and thyroglobulin molecules that enable the production of thyroid hormones. Between the thyroid follicles, there are thyroid C cells on the membranes that separate the follicles. C cells are also responsible for the secretion of the hormone calcitonin.

Thyroid cancer is cancer that originates from the thyroid tissue. There are those with a quiet and slow progression, as well as those with a fast and aggressive course. Thyroid cancers originate from thyroid follicular cells or C cells.

Thyroid cancers according to the cell type they originate from:

  • Thyroid follicular cells (95%)
  • Differentiated thyroid cancers
  • Papillary thyroid cancer
  • Follicular thyroid cancer
  • Hurthle cell thyroid cancer
  • Anaplastic thyroid carcinoma
  • Thyroid C cells (2%)
  • Medullary thyroid carcinoma

Thyroid cancers are three times more common in women than in men. Thyroid cancers can have many causes. Female gender, family history of thyroid cancer, and frequent exposure to radiation from the head and neck region during childhood are the main risk factors. However, existing thyroid diseases can also turn into cancer.

Genetic mutations can be found in almost all thyroid cancers. Genetic predisposition is an important disadvantage for thyroid cancers. In fact, mutations in differentiated thyroid cancers can be inherited in an autosomal dominant manner.

Diagnosis of thyroid cancers:

The definitive diagnosis of thyroid cancer is made by histopathological examination. In the histopathological examination, different features of each are evaluated. However, fine needle aspiration biopsy is not sufficient for the diagnosis of all thyroid cancers. Because the macromorphological structure of thyroid cancers is also very important for its definition. The biopsy technique should be decided on suitable patients and after a healthy evaluation according to appropriate criteria. For this, Bethesda criteria are generally used.

Papillary formation is typically seen in papillary thyroid cancers. Layers of cancer cells form surrounding a fibrovascular nucleus. Follicles are not seen. Papillary thyroid cancers also have different variants. Some variants do not form papillae and are expressed as follicular variants of papillary cancers. Papillary thyroid cancer variants such as long cell variant, columnar variant, insular carcinoma, and diffuse sclerosing variant are more aggressive than classical papillary thyroid cancer.

Follicular thyroid cancers originate from follicles and papillae are not seen in this type of cancer on tissue examination. They are very similar to follicular adenoma but can be separated from each other by vascular invasion. Follicular cancers have a worse prognosis.

Hurthle cell carcinoma is characterized by the appearance of eosinophilic oxyphilic cells (Hurthle cell) with abundant cytoplasm (oncocytes) and prominent nucleoli on pathological examination.

Medullary thyroid cancers originate from C cells. Typical spindle cells are seen on tissue examination.

Anaplastic thyroid carcinoma has tissues with many different mixed properties, with three different variants. The most distinctive feature is that it has abundant mitotic figures.

Thyroid cancers are often detected by the detection of a nodule in the thyroid gland. The patient’s family history and symptoms are examined. It is noteworthy that the patient has hoarseness, dysphagia and shortness of breath. In addition, a sudden increase in the size of the nodule with pressure symptoms such as Horner’s Syndrome, as well as a family history of thyroid cancer, require evaluation for malignancy. If there is frequent exposure to radiation, especially in childhood, further evaluation should be made. Systemic effects such as fatigue may also occur in these patients. Stiffness, immobility of the nodule and presence of neck lymph nodes in neck physical examination should trigger suspicion of malignancy and lead to further evaluation.

Anaplastic thyroid cancer is detected by a rapidly growing mass in the neck. It can manifest itself as the rapid emergence of pressure symptoms in the air and digestive system. Some patients may present with structural symptoms such as fever, weight loss and loss of appetite.

Thyroid hormone levels are evaluated in all patients with suspected thyroid disease, with or without a thyroid nodule. Hyperthyroidism usually carries a lower probability of malignancy. Radioactive iodine screening can be performed in these patients. Fine-needle aspiration biopsy is generally avoided if the iodine scan reveals hyperfunctioning thyroid or nodules.

Thyroid ultrasonography is the second important diagnostic step. Ultrasonography is used to examine risky thyroid tissues, evaluate adjacent thyroid tissues, examine surrounding lymph nodes and accompany fine needle aspiration biopsy. On ultrasonography, increased thyroid size, hypoechogenicity, irregular borders, microcalcifications, a solid internal structure, extrathyroidal extensions, and increased vascularity indicate a high-risk condition.

Molecular techniques can be used in cases where cytological examination is insufficient. In advanced cases, the extent of malignancy can be examined with computed tomography and magnetic resonance imaging.

In the evaluation of thyroid cancers, imaging techniques such as Technetium scintigraphy, Pet/Ct and color Doppler can also be applied.

Treatment of thyroid cancers:

Although treatments may vary according to the type of thyroid cancer, the main treatment method in thyroid cancers is surgical removal of the tumor. The procedure is performed after a detailed evaluation of the thyroid cancer before the operation, evaluation of the surrounding tissues and decision of the surgical technique. Surgical treatment technique may vary according to the type of thyroid cancer. Surgical complications may develop after surgery. They are usually controllable complications.

Radioactive iodine 131 ablation therapy can be applied to destroy cancer tissues remaining after surgery and to prevent recurrence. This treatment is applied only in patients with appropriate indications, by making a post-surgical risk classification. It is generally used more in recurrent diseases.

Thyroid hormone suppression treatment is applied to suppress the TSH secretion after surgery and to prevent the re-development of the remaining thyroid cells.

In patients with advanced metastases from thyroid cancers, the patient’s condition should be evaluated and chemotherapy treatment may be required in suitable patients. Systemic chemotherapy is applied in cases where it will be more beneficial by evaluating the risk and benefit.

Even if the same treatment methods are applied for anaplastic thyroid cancers, it is a fast growing, rapidly progressing and aggressive cancer type. The mortality rate in these cancers is close to 100%. Palliative surgical treatments suitable for the patient can be evaluated.