The abnormal proliferation of thyroid cells can result in thyroid cancer. However, the actual cause is still unknown. In general, patients are middle-aged or older; and women have a higher risk than men. According to the Hong Kong Cancer Registry of the Hospital Authority, there are 795 new cases in 2014.
Fortunately, the survival rate of thyroid cancer is very high. If it is diagnosed early and treated properly, most cases can be cured satisfactorily.
Risk Factors
- People aged 40 or above
- Radiation treatment in the neck, especially in young patients
- Family history or hereditary conditions
- Iodine deficiency in the diet
Symptoms
- Painless growing lump(s) in the front of the neck
- Hoarseness
- Neck pain or sore throat, sometimes with ear pain as well
- Trouble in swallowing or breathing, sometimes with a feeling of oppression
Examinations and Diagnosis
Most of the newly diagnosed thyroid cancers in Hong Kong are found early, so the cure rate is very high and the mortality rate is very low. However, as the latent period is very long, long-term regular monitoring for persistent disease or a recurrence is important.
Thyroid cancer screening and diagnosis
1) Blood test
2) Ultrasound thyroid scan
3) Fine needle aspiration biopsy
4) Surgical biopsy
To determine metastasis and the cancer stage
1) Computerized Tomography (CT Scan)
2) Thyroid Radioisotope Scan
Treatment
Treatment of thyroid cancer depends on the patient’s condition, which is based on the type, size, location, and degree of metastasis of the tumour(s), as well as the age and physical condition of the patient. Surgery is the main treatment of thyroid cancer, with radiotherapy as an adjuvant therapy.
Surgery
Depending on the patient’s condition, the doctor may decide to remove only the affected thyroid or the entire thyroid gland. During the operation, the doctor will also check whether the nearby lymph nodes have been affected by the cancer or not. If the cancer has spread to nearby areas, the doctor will remove the tissues around the thyroid as well.
Radioactive Iodine Therapy
This is an in vivo radiation therapy. Patients have to take into the body radioactive iodine in the form of a capsule. Cancer cells which are not completely removed or have metastasized will take up the iodine and then be destroyed by the radioactive material, same for normal thyroid.
External-beam Radiation Therapy (radiotherapy, electrotherapy)
For the remaining cancerous tumours in the neck or those which cannot be surgically removed, doctors may consider external-beam radiation therapy.
Chemotherapy or Target Therapy
These are systemic treatment using drugs to destroy cancer cells. However, it is less common in thyroid cancer treatment, unless the cancer has spread or for patients with a recurrence after other treatments.
Hormonal Therapy
Thyroid hormone replacement is necessary after total thyroid removal. Suitable dosage adjustment of thyroid hormone can also suppress re-growth of residual thyroid cancer, if any.
