Thyroid Cancer: Symptoms, Causes, Treatment, and Beyond

What is Thyroid Cancer?

Thyroid cancer is a type of malignancy that develops in the thyroid gland, a butterfly-shaped organ located at the base of the neck. This small but vital gland is part of the endocrine system and plays a crucial role in regulating metabolism, heart rate, blood pressure, and body temperature through the production of thyroid hormones.

While thyroid cancer isn’t among the most common types of cancer, its incidence has been steadily rising over the past few decades. According to the American Cancer Society, it’s estimated that about 44,280 new cases of thyroid cancer will be diagnosed in the United States in 2021. Despite this increase, the prognosis for most types of thyroid cancer remains excellent, especially when detected and treated early.

Types of Thyroid Cancer

Thyroid cancer is not a single disease but rather a group of cancers that originate in the thyroid gland. Understanding the different types is crucial as they vary in their aggressiveness, treatment approach, and prognosis.

Papillary Thyroid Cancer (PTC)

• Most common type, accounting for about 80% of all cases
• Tends to grow slowly and often spreads to lymph nodes in the neck
• Excellent prognosis with a 5-year survival rate of over 95%
• Often affects people between the ages of 30 and 50
• Can occur in children and is the most common type in this age group

Follicular Thyroid Cancer (FTC)

• Second most common, making up about 10-15% of cases
• More likely to spread via blood vessels to distant organs like lungs and bones
• Generally has a good prognosis but slightly worse than PTC
• More common in areas with iodine deficiency
• Typically affects people over 50

Medullary Thyroid Cancer (MTC)

• Accounts for about 2% of thyroid cancers
• Develops from C cells (parafollicular cells) that produce calcitonin
• Can be sporadic (75% of cases) or hereditary (25% of cases)
• Hereditary MTC is associated with Multiple Endocrine Neoplasia type 2 (MEN2)
• More challenging to treat as it doesn’t respond to radioactive iodine therapy

Anaplastic Thyroid Cancer (ATC)

• Rarest form, less than 2% of cases, but most aggressive
• Typically occurs in older adults over 60
• Rapid growth and early spread to other organs
• Poor prognosis with a median survival of about 5 months
• Requires immediate and aggressive treatment

Other Rare Types

• Hürthle cell carcinoma: A variant of follicular cancer
• Poorly differentiated thyroid cancer: More aggressive than PTC and FTC
• Thyroid lymphoma: Rare cancer of the immune system cells in the thyroid

Risk Factors

While the exact cause of thyroid cancer is not fully understood, several risk factors have been identified:

Radiation Exposure

• The most well-established risk factor
• Includes medical treatments (e.g., radiation therapy for other cancers) and environmental exposures (e.g., nuclear accidents)
• Risk is higher if exposure occurs in childhood

Gender and Age

• Women are three times more likely to develop thyroid cancer than men
• Can occur at any age, but risk increases with age for most types
• PTC is more common in younger adults, while FTC and ATC are more common in older adults

Family History and Genetics

• About 5% of PTCs are familial
• MTC can be hereditary (MEN2 syndrome)
• Other genetic conditions like Cowden syndrome and familial adenomatous polyposis also increase risk

Iodine Intake

• Both deficiency and excess can increase risk
• Deficiency is associated with follicular and anaplastic carcinomas
• Excess iodine intake may increase risk of papillary carcinoma

Other Factors

• Obesity
• Hormonal factors (higher risk in women of reproductive age)
• Pre-existing thyroid conditions (e.g., goiter, thyroid nodules)

Symptoms and Signs of Thyroid Cancer

Early-stage thyroid cancer often doesn’t cause noticeable symptoms, which is why it’s sometimes discovered incidentally during routine physical exams or imaging studies for unrelated conditions. As the cancer grows, it may cause:

Neck Lump or Nodule

• The most common sign
• Usually painless
• May be felt by the patient or noticed by a healthcare provider during an exam

Neck Pain

• Can range from mild discomfort to more severe pain
• May radiate to the jaw or ears

Voice Changes

• Hoarseness or other voice changes that persist
• Caused by the tumor pressing on the laryngeal nerves

Swallowing Difficulties

• Feeling of a lump in the throat when swallowing
• In advanced cases, actual difficulty swallowing (dysphagia)

Breathing Problems

• Shortness of breath or noisy breathing
• Usually only in very advanced cases where the tumor is large enough to compress the trachea

Lymph Node Swelling

• Swollen lymph nodes in the neck
• May indicate that the cancer has spread to the lymphatic system

Hyperthyroidism Symptoms

• In rare cases, the tumor may produce excess thyroid hormones
• Symptoms can include rapid heartbeat, nervousness, unexplained weight loss, and increased appetite

It’s important to note that these symptoms can also be caused by non-cancerous conditions. However, any persistent symptoms should be evaluated by a healthcare professional.

Diagnosis

The diagnosis of thyroid cancer typically involves a combination of physical examination, blood tests, imaging studies, and biopsy. The process usually follows these steps:

Physical Examination

• The doctor feels the neck, checking for lumps or swelling
• Examines the lymph nodes in the neck area

Blood Tests

• Thyroid function tests (TSH, T3, T4) to check overall thyroid health
• Calcitonin and carcinoembryonic antigen (CEA) levels may be checked if MTC is suspected
• Thyroglobulin levels are often monitored after treatment to check for recurrence

Imaging Studies

• Ultrasound: Usually the first and most important imaging test
  • Can determine size and characteristics of nodules
  • Guides FNA biopsy
• CT scan: Provides detailed cross-sectional images of the neck
• MRI: Useful for evaluating soft tissue involvement
• PET scan: May be used to detect spread of cancer or recurrence after treatment

Fine Needle Aspiration (FNA) Biopsy

• A thin needle is used to extract cells from the suspicious area
• Cells are examined under a microscope by a pathologist
• Results are usually reported using the Bethesda System for Reporting Thyroid Cytopathology

Molecular Testing

• In cases where FNA results are indeterminate
• Looks for specific genetic mutations associated with thyroid cancer (e.g., BRAF, RAS, RET/PTC)
• Can help determine if surgery is necessary for indeterminate nodules

Laryngoscopy

• May be performed if there are voice changes
• Checks the function of the vocal cords

Staging

If thyroid cancer is diagnosed, the next step is staging, which determines the extent of the disease. The TNM system is used for staging:

• T (Tumor): Size and extent of the main tumor
• N (Nodes): Spread to nearby lymph nodes
• M (Metastasis): Spread to distant sites

Based on these factors, thyroid cancer is staged from I to IV, with stage I being the least advanced and stage IV being the most advanced. The staging process may involve additional imaging studies like chest X-rays or bone scans.

Treatment Options for Thyroid Cancer

Treatment for thyroid cancer is highly individualized and depends on factors such as the type and stage of cancer, the patient’s age and overall health, and personal preferences. The main treatment options include:

Surgery

• The primary treatment for most thyroid cancers
• Types of surgery include:
  • Lobectomy: Removal of the affected lobe of the thyroid
  • Total thyroidectomy: Removal of the entire thyroid gland
  • Lymph node dissection: Removal of nearby lymph nodes if cancer has spread
• Risks include damage to the parathyroid glands and laryngeal nerves

Radioactive Iodine (RAI) Therapy

• Often used after surgery to destroy any remaining thyroid tissue or cancer cells
• Patient takes radioactive iodine orally, which is absorbed by thyroid cells
• Effective for PTC and FTC, but not for MTC or ATC
• Requires isolation for a period after treatment due to radioactivity

Thyroid Hormone Therapy

• Necessary for life after total thyroidectomy
• Also used to suppress TSH production, which can stimulate growth of any remaining cancer cells
• Requires regular monitoring and dose adjustments

External Beam Radiation Therapy

• Used in advanced cases or for cancers that don’t respond to RAI
• May be used for MTC and ATC
• Can cause side effects like skin irritation and fatigue

Chemotherapy

• Not typically used for well-differentiated thyroid cancers
• May be used for advanced or anaplastic thyroid cancers
• Often combined with radiation therapy

Targeted Therapy

• Drugs that target specific mutations or changes in cancer cells
• Examples include sorafenib, lenvatinib, and cabozantinib
• Used for advanced thyroid cancers that don’t respond to other treatments

Alcohol Ablation

• Used for small thyroid cancers or recurrent cancers in lymph nodes
• Ethanol is injected directly into the tumor to destroy cancer cells

Active Surveillance

• For very small, low-risk papillary thyroid cancers
• Involves regular monitoring without immediate treatment
• Treatment is initiated if the cancer shows signs of growth or spread

Follow-up and Monitoring

After initial treatment, ongoing monitoring is crucial to detect any recurrence or spread of the cancer. This typically involves:

Regular Check-ups

• Physical exams and neck palpation
• Frequency depends on the type and stage of cancer, usually every 3-6 months initially, then annually

Blood Tests

• Thyroglobulin levels (for PTC and FTC)
• Calcitonin and CEA levels (for MTC)
• TSH and thyroid hormone levels to ensure proper hormone replacement

Imaging Studies

• Neck ultrasounds
• Whole-body radioiodine scans (for PTC and FTC)
• Other imaging (CT, MRI, PET) as needed

Conclusion

While a thyroid cancer diagnosis can be frightening, it’s important to remember that most types have an excellent prognosis when detected and treated early. Advances in diagnostic techniques and treatment options continue to improve outcomes for patients. With proper care and follow-up, many people with thyroid cancer are able to return to their normal lives and activities.

If you notice any unusual symptoms or have concerns about thyroid cancer, don’t hesitate to consult with your healthcare provider. Early detection and treatment are key to the best possible outcomes.