Thyroid cancer: when thyroid's cells grow out of control

Thyroid cancer is a type of cancer that begins in the thyroid gland, an endocrine gland composed of two connected lobes located at the front of the neck, below the laryngeal prominence.

The thyroid gland secretes thyroid hormones, which influence metabolic rate, protein synthesis, appetite, intestinal motility, absorption of substances, and play a significant role in bodily development. Any functional disorder of this gland can lead to severe systemic problems and is, therefore, carefully regulated. The thyroid gland consists of two main types of cells: follicular cells and C cells. The primary role of follicular cells is to produce thyroid hormones that regulate metabolism, while C cells synthesize calcitonin, which controls calcium levels in the body.

Thyroid cancer generally originates in follicular cells but may also arise in C cells.

Doctors classify thyroid cancer into three main types based on the origin of the cells involved:

• Differentiated thyroid cancer (DTC): includes papillary, follicular, and Hürthle cell cancers
  • Papillary cancer: accounts for about 8 out of 10 thyroid cancers. Papillary cancers tend to grow very slowly
  • Follicular cancer: also called follicular carcinoma or adenocarcinoma, it is the second most common type
  • Hürthle cell cancer: a more challenging type to treat

• Medullary thyroid cancer (MTC): develops from the thyroid’s C cells. This type is harder to detect and treat
  • Sporadic MTC: not inherited
  • Familial MTC: inherited, with 20%-25% of cases occurring across generations in a family. These cancers often develop in childhood or early adulthood and may spread early

• Anaplastic thyroid cancer: a highly aggressive, undifferentiated tumor. It is termed "undifferentiated" because the cancer cells do not closely resemble normal thyroid cells under a microscope

Various factors can increase the risk of thyroid cancer. Some, like avoiding radiation exposure, can be controlled, while others, such as hereditary conditions, cannot.

Risk factors for thyroid cancer include:

• Being female (women have a higher risk than men)
• Hereditary conditions
• A diet low in iodine
• Radiation exposure

Although some cancers may remain undetectable until advanced stages, certain symptoms can signal their presence:

• A lump that can be felt through the skin of the neck
• Voice changes, including increased hoarseness
• Difficulty swallowing
• Neck and throat pain
• Swollen lymph nodes in the neck

The survival rate for thyroid cancer is closely linked to the tumor stage and also depends on the type of cells involved. For the three main types of thyroid cancer discussed above, the 5-year survival rate for early stages (I and II) is nearly 100%. However, survival rates drop in later stages. For stage III, survival rates are approximately 80%. In stage IV, papillary and follicular thyroid cancer have a 5-year survival rate of around 50%, while medullary thyroid cancer survival rates are significantly lower. Anaplastic thyroid cancer, being rare but extremely lethal, has a survival span of only 2 to 6 months after diagnosis.

IMPORTANT: EARLY CANCER DIAGNOSIS IS CRUCIAL, AS CANCERS IDENTIFIED AT AN EARLY STAGE—BEFORE SIGNIFICANT GROWTH OR SPREADING—ARE MORE LIKELY TO BE SUCCESSFULLY TREATED. CONVERSELY, CANCERS THAT HAVE METASTASIZED TO OTHER ORGANS ARE HARDER TO TREAT, AND SURVIVAL PROBABILITIES ARE SIGNIFICANTLY LOWER.

Various techniques have been employed to diagnose thyroid cancer, including imaging methods, biopsies, blood tests, and physical examinations. However, these approaches have limitations, patient stress associated with tissue extraction during biopsies. Low predictive accuracy of blood tests, poor resolution of physical examinations and high cost of advanced methods, such as computed tomography, positron emission tomography, and ultrasound systems.