Thyroid cancer develops in the thyroid gland at the front of the neck — a small, butterfly-shaped gland that produces hormones regulating metabolism. Thyroid cancer is not uncommon in Hong Kong, with significantly more women affected than men, and it tends to occur at a younger age than many other cancers.
Hearing the word "cancer" need not be devastating: the most common type, papillary thyroid cancer, grows slowly and has an extremely high cure rate, making it one of the best-prognosis cancers. Even for more challenging types, targeted therapies and other new options have emerged in recent years.
Causes and Risk Factors
The cause of thyroid cancer is largely unknown. The most established risk factor is radiation exposure to the neck during childhood or adolescence (such as from older forms of radiation therapy). Some thyroid cancers are hereditary: familial medullary thyroid cancer is linked to RET gene mutations, and those with a family history may consider genetic testing.
Other observed associations include: being female (incidence is about three times that of men), abnormal iodine intake (too much or too little), and obesity. Notably, with the widespread use of ultrasound, more and more tiny thyroid cancers are being "incidentally found" during examinations — many of which are slow-growing, low-risk types that only require monitoring.
Common Symptoms and Warning Signs
The most common presentation of thyroid cancer is a painless lump or nodule in the front of the neck, often noticed while looking in the mirror, touching the neck, or during a physical examination. Most thyroid nodules are benign; only a minority are cancerous.
Warning signs to watch for include: a lump that grows rapidly, is hard and fixed in place, hoarseness (from tumor affecting the recurrent laryngeal nerve), difficulty swallowing or breathing, and swollen lymph nodes on the side of the neck. If hoarseness lasts more than two weeks, especially with a neck lump, seek medical evaluation promptly.
Diagnosis and Staging Concepts
Neck ultrasound is the first-line examination, assessing the size, shape, and suspicious features of nodules. Suspicious nodules are sampled with fine-needle aspiration (FNA) for cytology, which can confirm or rule out cancer in most cases. Blood thyroid function tests assess gland status but cannot distinguish benign from malignant nodules.
Thyroid cancer has four main types: papillary (most common, best prognosis), follicular, medullary (associated with RET gene), and anaplastic (rare but highly aggressive). Staging considers age in addition to TNM — differentiated thyroid cancer in patients under 55 generally has an excellent prognosis.
Overview of Treatment Options
Surgery is the main treatment, removing half or all of the thyroid depending on the situation, along with affected neck lymph nodes. Differentiated cancers (papillary, follicular) are often followed by radioactive iodine therapy (commonly called "I-131") to eliminate residual cancer cells; after surgery, long-term thyroid hormone replacement is needed to supplement hormones and suppress recurrence. For very low-risk microcarcinomas, some patients may choose regular monitoring instead of immediate surgery.
For advanced differentiated cancers that no longer respond to radioactive iodine, as well as medullary and anaplastic cancers, targeted therapies (such as multi-kinase inhibitors, RET or NTRK inhibitors) have become important options — which is why genetic testing is increasingly important in thyroid cancer.
Clinical Trials: One More Treatment Option
For refractory thyroid cancer, clinical trials of next-generation targeted drugs and gene-directed therapies are ongoing, offering more choices for patients whose cancer no longer responds to radioactive iodine.
The CancerLink platform can match patients with thyroid cancer-related clinical studies recruiting in Hong Kong based on cancer type, stage, and genetic mutations. Once successfully matched and enrolled, study-related treatment costs are fully covered.
If you notice a neck lump, start with an ultrasound — it's the simplest first step. Even if thyroid cancer is diagnosed, take heart: most thyroid cancers progress slowly and have well-established treatments. You can choose the most suitable plan with your doctor calmly, without needing to rush.