Resource persons: Dr Tan Teik Hin, Consultant Nuclear Medicine Physician and Dr Wong Mei Wan, Consultant Breast and Endocrine Surgeon at Sunway Medical Centre, Sunway City (SMC)

Thyroid cancer, one of the most treatable cancers, remains under-discussed in Malaysia. According to The Malaysia National Cancer Registry Report 2017-2021, it ranks as the 8th most common cancer among women, with an incidence rate of 4.2 per 100,000 populations. Women are more affected than men, a trend that researchers believe may be influenced by hormonal factors, particularly estrogen. While laboratory studies suggest estrogen may stimulate thyroid cell growth, large-scale population studies have not found a clear link between estrogen levels and increased thyroid cancer risk.

The thyroid gland, butterfly-shaped and often overlooked, sits at the base of the neck, quietly regulating metabolism, energy, and temperature. But when cancer strikes this small organ, symptoms are often subtle until they’re not.

Often dubbed a silent disease, thyroid cancer can develop without obvious symptoms. In many cases, a persistent neck lump or subtle voice changes are the first signs. While awareness has improved and more cases are now caught early through routine health screenings, confusion between thyroid cancer and common thyroid issues like hypothyroidism, goiter, and cancer continues to delay timely action.

Early warning signs

Dr Tan Teik Hin

“The thyroid produces thyroxine, a hormone essential for metabolism. Too much makes you restless and energetic, too little and you feel sluggish and cold,” explains Dr Wong. However, thyroid cancer isn’t about hormones. “Most patients with thyroid cancer have normal thyroid function. The cancer is typically a physical growth or nodule within the gland; it doesn’t cause hyperthyroidism or hypothyroidism, and it’s not caused by them either,” clarifies Dr Tan.

Diagnosis usually starts when a patient notices a hard lump in the neck. Other symptoms may include voice changes, difficulty swallowing, or swollen lymph nodes. Not all nodules are cancerous. Dr Wong says ultrasound and biopsy help distinguish benign from malignant ones.
Unlike many other cancers, thyroid cancer in Malaysia is not strongly linked to lifestyle factors like smoking. Family history can be a factor. “There are some hereditary types, but not every thyroid cancer is genetic. We only test when the family pattern is evident,” says Dr Wong. About two-thirds of her patients are women, which echoes a global trend.

Stages and survival rate

Dr Wong Mei Wan

Most Malaysians today are catching thyroid cancer at Stage 1, often through health screenings. “A decade ago, we used to see more late-stage cases, often Stage 3 or 4. This is a very encouraging shift,” says Dr Tan.

Dr Tan says that about 85% of thyroid cancers are slow-growing, mainly papillary or follicular types, and usually respond well to treatment. But once the cancer reaches Stage 4 and spreads to the lungs or bones, survival drops to below 50%.

Both doctors agree that while thyroid screening is not routine in Malaysia, public education remains vital. “If you feel a persistent lump in your neck, don’t wait to get it checked. An ultrasound and blood test are simple, accessible, and can be done at most clinics,” says Dr Wong.

Treatment pathways: surgery and radioactive iodine

Treatment often begins with surgery. “Once the tumor is removed, we check how aggressive it is. If it’s high-risk, we usually follow up with radioactive iodine (RAI) therapy,” explains Dr Tan.

RAI serves both treatment and diagnostic purposes. “It clears out any leftover cancer cells and lets us scan for hidden spread,” says Dr Tan. For small tumors under 1 cm, surgery alone may be enough. He reassures patients who are concerned about radiation: “Radioactive iodine is chemically identical to natural iodine in our bodies. It’s safe, well-tolerated, and rarely causes allergies. The concern is usually the word ‘radioactive,’ but it’s nothing like external beam radiation therapy”, he adds, emphasizing that strict patient safety protocols are always adhered to.

After treatment recurrence and long-term monitoring

While outcomes are usually good, recurrence can happen, often in the lymph nodes, even years later. “That’s why long-term follow-up is critical,” says Dr Wong.

Post-surgery, patients typically need lifelong thyroid hormone replacement. “It’s similar to taking supplements; they are well accepted, and most patients can adjust quickly,” says Dr Wong.

For Stage 1 and 2 patients, Dr Tan recommends checks every six months for two years, then yearly for up to five. After that, follow-up can be based on comfort and risk.

Drugs like tyrosine kinase inhibitors (TKIs) provide new options for advanced or resistant cases. “These are used when RAI is no longer effective. They shrink tumors before surgery or manage metastatic disease,” says Dr Tan. However, side effects such as fatigue, skin problems, proteinuria, or hypertension must be monitored closely.

The experts added that while thyroid cancer often grows slowly, early detection makes a big difference. “The earlier we treat, the better the outcome, so take your body seriously.”