Thyroid cancer

Thyroid Cancer

Thyroid Gland

The thyroid gland is crucial for regulating hormones and metabolism. It absorbs iodine from the blood to produce thyroid hormones that control bodily functions like energy use, heart rate, and body temperature. The gland is located at the front of the neck, with two lobes on either side of the trachea. Normally, the thyroid gland is not visible or palpable unless it is enlarged, which can lead to a condition called goitre. Not all lumps in the thyroid are cancerous.

Thyroid cancer occurs when thyroid cells grow uncontrollably and form a mass. Two types of cells exist within the thyroid gland:

1. Follicular Cells: These produce thyroid hormones that regulate metabolism and energy usage.

2. C Cells: These cells produce calcitonin, a hormone involved in calcium metabolism.

Types of Thyroid Cancer

1. Papillary Thyroid Cancer:

• The most common form of thyroid cancer.

• Grows slowly and often affects one lobe of the gland, although it can occur on both sides in 10-20% of cases.

• It can spread to lymph nodes.

2. Follicular Thyroid Cancer:

• Less common and spreads slowly.

• Spreads rarely to lymph nodes but can spread to other body parts.

3. Hurthle Cell Cancer:

• A subtype of follicular cancer with a higher tendency to spread to lymph nodes.

4. Medullary Thyroid Cancer (MTC):

• Accounts for 3% of thyroid cancers.

• Originates in the C cells and can be related to Multiple Endocrine Neoplasia Type 2 (MEN 2), a genetic condition.

• Early detection is critical for effective treatment.

5. Anaplastic Thyroid Cancer:

• Very rare but aggressive.

• Accounts for only 1% of thyroid cancers, and treatment can be challenging.

Statistics

According to Globocan 2020, about 20,432 new cases of thyroid cancer are reported annually in India, ranking it 19th among all cancers.

Risk Factors

• Gender: Women are more likely to develop thyroid cancer (4 out of 3 cases).

• Age: Common between 20-50 years.

• Genetics: Family history increases the risk.

• Radiation Exposure:

• Radiotherapy to the head and neck for other cancers.

• Radioactive iodine exposure during childhood.

• Nuclear weapon testing exposure.

• Iodine Deficiency: Lack of iodine can increase the risk.

• Race: Higher incidence among Caucasians and Asians.

• Breast Cancer History: Recent studies indicate a potential link between breast and thyroid cancer.

Symptoms

Not all thyroid cancers present symptoms. However, common signs include:

• Lump at the front of the neck

• Hoarseness or voice changes

• Swollen lymph nodes in the neck

• Difficulty swallowing

• Shortness of breath

• Throat or neck pain

• Persistent cough without a cold

Diagnosis

1. Physical Examination:

• The doctor palpates the thyroid, lymph nodes, and other neck areas for abnormalities.

2. Blood Tests:

• Thyroid hormone levels (T3, T4)

• Thyroid-stimulating hormone (TSH)

• Thyroglobulin (Tg) and Tg Antibodies (TgAb)

• Specific tests for medullary thyroid cancer

3. Ultrasound:

• Detects abnormalities and determines if a lump is solid or fluid-filled.

4. Biopsy:

• Fine Needle Aspiration (FNA): A needle extracts cells from the lump for examination.

• Surgical Biopsy: If FNA results are inconclusive, the doctor may recommend removing part or all of the thyroid lobe.

5. Radionuclide Scanning:

• Uses radioactive iodine (I-131 or I-123) to scan the thyroid and detect cancerous cells.

6. Imaging Tests:

• X-ray, CT Scan, PET-CT Scan

Cancer Staging

• T Staging (Tumor):

• T1a: Tumor ≤1 cm and limited to the thyroid.

• T1b: Tumor >1 cm but ≤2 cm, confined to the thyroid.

• T2: Tumor >2 cm but ≤4 cm, still within the thyroid.

• T3: Tumor >4 cm without extending outside the thyroid.

• T4a: Tumor invades surrounding tissues, such as the trachea or esophagus.

• T4b: Tumor spreads beyond the thyroid to distant tissues.

• N Staging (Lymph Nodes):

• N1a: Cancer spreads to nearby lymph nodes.

• N1b: Cancer spreads to distant lymph nodes.

• M Staging (Metastasis):

• M1: Cancer has spread to distant organs.

Treatment

1. Surgery

• Lobectomy: Removal of the affected lobe.

• Near-total Thyroidectomy: Almost the entire thyroid is removed.

• Total Thyroidectomy: Complete removal of the thyroid gland.

• Neck Dissection: Removal of lymph nodes if cancer has spread.

2. Hormone Therapy

After thyroid removal, levothyroxine tablets are prescribed to replace thyroid hormones.

• Taken daily on an empty stomach at the same time each day.

• Regular blood tests are required to monitor hormone levels and adjust the dosage.

• Calcium and Vitamin D supplements may also be prescribed.

3. Radioactive Iodine Therapy

Radioactive iodine (I-131) is used to destroy remaining cancer cells after surgery.

• Administered as a liquid or pill.

• Patients may need to stay in the hospital for a few days during treatment.

• A low-iodine diet is recommended before treatment.

4. External Beam Radiation Therapy

• Used in specific cases where cancer spreads to nearby tissues.

• High-energy beams are directed at the affected area to kill cancer cells.

5. Targeted Therapy

Certain drugs target specific genetic mutations and proteins in thyroid cancer cells:

• Sorafenib

• Lenvatinib

• Larotrectinib

• Entrectinib

• Pralsetinib

• Vandetanib

• Cabozantinib

Follow-Up Care

After treatment, regular follow-ups are essential to monitor for recurrence and manage side effects. This includes:

• Physical examinations

• Blood tests

• Ultrasound and imaging tests

Thyroid cancer, particularly in its early stages, is highly treatable with a combination of surgery, radioactive iodine therapy, and hormone replacement. With timely detection and appropriate care, most patients achieve full recovery. Regular follow-ups play a crucial role in maintaining health and preventing recurrence.

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