What Is Papillary Thyroid Cancer? Is It Dangerous and How Is It Treated?

Papillary thyroid cancer is the most common type of thyroid cancer and usually the slowest-growing. About 80 per cent of thyroid cancers are of this type. When detected at an early stage, it usually responds very well to treatment; the main treatment is surgery. For very small, low-risk tumours, close monitoring instead of immediate surgery may also be discussed as an option in suitable patients.

Seeing the words “papillary carcinoma” on a biopsy report frightens most people. That fear is understandable; but the course of this type is usually very different from the picture the word “cancer” brings to mind. In this article I explain what the diagnosis means and the next steps, one by one.

What is papillary thyroid cancer?

Papillary thyroid cancer is a cancer that develops from the hormone-producing cells of the thyroid gland. It takes its name from the finger-like (papillary) structures it forms under the microscope.

A distinctive feature of this type is that it can spread to the lymph nodes in the neck. Even when lymph nodes are involved, the course of the disease is often good; however, because this determines the extent of surgery, the neck is always assessed with ultrasound at diagnosis.

Why are we hearing about it more often in recent years?

In a large registry study in the USA covering 1974–2013, the incidence of thyroid cancer rose by an average of 3.6 per cent per year; most of this increase came from the papillary type. More frequent detection of very small tumours as ultrasound became widespread is an important reason for this rise. The same study shows that advanced-stage papillary cancers also increased somewhat; in other words, the increase cannot be explained entirely by “more screening”.

Is papillary thyroid cancer dangerous? Is it fatal?

This is the question most often asked in search engines. The honest answer: in the great majority of cases, papillary thyroid cancer is a treatable cancer with good long-term outcomes; but it is not the same for every patient.

In the same registry study, the death rate from thyroid cancer remained at about 0.4–0.5 per 100,000 people per year. The main factors that determine the outcome are:

• Tumour size and whether it extends beyond the thyroid capsule
• Lymph node involvement and how extensive it is
• Distant spread (lungs, bone); rare, but it changes the picture
• Age: the course is generally better in younger patients
• Microscopic subtype: some subtypes can behave more aggressively

That is why the individual answer to “is it dangerous?” can only be given once the pathology report and imaging results have been evaluated together.

What are the symptoms?

Papillary thyroid cancer often causes no symptoms. It is usually noticed as a painless nodule in the neck, or found incidentally on an ultrasound performed for another reason. As it progresses, the following may occur:

• A firm, growing swelling in the neck
• Palpable lymph nodes in the neck
• Persistent hoarseness
• Difficulty swallowing or breathing

I explained which neck nodules need to be assessed in my article on nodules in the throat.

How is it diagnosed?

1. Neck ultrasound: the structure of the nodule and the lymph nodes in the neck are assessed.
2. Fine-needle aspiration biopsy: cells are taken from the suspicious nodule; the result is reported according to the Bethesda system.
3. Blood tests: thyroid hormones and TSH.
4. Vocal cord assessment: before surgery, the movement of the vocal cords is checked with an endoscope.

How is it treated?

The main treatment is surgery. The extent of the operation is determined by the characteristics of the tumour:

Situation	General approach
Tumour smaller than 1 cm, low risk	In suitable patients, close monitoring or removal of one lobe of the thyroid (lobectomy)
Tumour of 1–4 cm, not extending beyond the capsule, no lymph node involvement	Lobectomy or removal of the entire thyroid (total thyroidectomy)
Tumour larger than 4 cm, extension beyond the capsule, lymph node involvement or distant spread	Total thyroidectomy; neck dissection if lymph nodes are involved

This table is a general framework; it is based on the recommendations of the American Thyroid Association guidelines, and the decision is made individually. After surgery, radioactive iodine treatment is planned by nuclear medicine in suitable patients. If the entire thyroid has been removed, thyroid hormone is taken for life.

During surgery, the nerves that move the vocal cords and the parathyroid glands that regulate calcium are preserved. I covered this in detail in the article on thyroid cancer and protecting the vocal cords.

Is monitoring possible for very small tumours?

Papillary cancers smaller than 1 cm are called papillary microcarcinomas. In a study from Japan that followed 5,646 patients between 1993 and 2019, the tumour grew by 3 mm or more in 3.8 per cent of patients with low-risk microcarcinomas who chose regular ultrasound monitoring instead of immediate surgery. None of the patients in the study died of thyroid cancer; the researchers regarded monitoring as a valid first option for suitable patients.

Monitoring is not suitable for everyone. The tumour’s proximity to the windpipe or to the vocal cord nerve, lymph node involvement, the ability to attend regular follow-up and the patient’s preference determine the decision.

What does follow-up look like after surgery?

Follow-up is carried out together with endocrinology and nuclear medicine:

• Regular blood tests (thyroid hormones, TSH and thyroglobulin)
• Neck ultrasound at set intervals
• Additional imaging if needed

Follow-up intervals are set according to the initial risk level and become less frequent over time. Diagnosis, surgery and the process afterwards are described together on the thyroid cancer page.