Thyroid Cancer

What is Thyroid Cancer ?

Although thyroid cancer occurs in all age-groups, patients who have had radiation therapy in the neck area are especially susceptible. Papillary and follicular carcinomas are the most common forms of thyroid cancers and are usually associated with the longest survival times.

Papillary carcinoma accounts for about half of thyroid cancer in adults. It can occur at any age but is most common in young adult females. Usually multifocal and bilateral, it metastasizes slowly into regional nodes of the neck, mediastinum, lungs, and other distant organs. It is the least virulent form of thyroid cancer.

Causes of Thyroid Cancer

Besides exposure to radiation, suspected causes of thyroid cancer include prolonged secretion of thyroid stimulating hormone (TSH) through radiation or heredity, familial predisposition, and chronic goiter.

Signs & Symptoms of Thyroid Cancer

• A thyroid nodule
• Cough or cough with bleeding
• Difficulty swallowing
• Enlargement of the thyroid gland
• Hoarseness or changing voice
• Neck swelling

Diagnostic Tests

Fine-needle aspiration biopsy may help to differentiate benign from malignant thyroid nodules. Histologic analysis helps stage the disease and guide treatment.

Thyroid scan may differentiate functional nodes (rarely malignant) from hypo functional nodes (commonly malignant) by measuring how readily nodules trap isotopes compared with the rest of the thyroid gland. In thyroid cancer, scintigraphy findings may demonstrate a "cold," nonfunctioning nodule.

Ultrasonography evaluates changes in the size of thyroid nodules after thyroxine suppression therapy, guides fine-needle aspiration, and detects recurrent disease.

Magnetic resonance imaging and computed tomography scanning provide information for treatment planning because they establish the extent of the disease within the thyroid and in surrounding structures.

Treatment

Treatment depends on the type, size and stage of the cancer, and the patient’s age and health. Options may include:

• Surgery - the favoured treatment for papillary, follicular and medullary cancers. The thyroid gland is removed, either whole or in part depending on the size of the cancer and how much of the gland is affected. Nearby lymph nodes may also be removed.
• Radiation therapy - Radioactive iodine is used to kill any remaining thyroid hormone-producing cells. This normally requires the patient to stop thyroxine treatment for a few weeks to cause thyroid stimulating hormone (TSH) levels to rise and thereby stimulate the thyroid cells to absorb the radioactive iodine. Patients can become significantly hypothyroid during this period. External radiation is frequently used for medullary and anaplastic cancer, and for tumours which do not respond to radioactive iodine.
• Hormone therapy - patients require thyroid hormone replacement in the form of thyroxine following surgery. The doses given are generally higher than for other hypothyroid patients, in order to suppress the production of thyroid stimulating hormone and thereby suppress the growth of thyroid cells.
• Chemotherapy - drugs that kill cancer cells are used for the cancers that do not involve the thyroid hormone-producing cells.

Prevention Tips

As most cases of thyroid cancers are sporadic and not associated with any risk factors, there is usually no method to prevent the development of thyroid cancer. Careful examination of the thyroid and consideration of screening for patients at high risk could be considered, though the general prevention of thyroid cancers is impossible.