The thyroid is a gland in the neck that creates hormones that help regulate bodily functions such as metabolism and heart rate. Thyroid cancer is an uncommon form of cancer that develops in the thyroid cells.

The thyroid plays an important role in producing hormones to regulate the body. Evidence suggests that in 2021, there are roughly 44,280 new cases of thyroid cancer, with 12,150 cases occurring in males and 32,130 occurring in females.

In this article, we will discuss thyroid cancer, including symptoms, causes, different types, and treatment options.

A person with thyroid cancer.Share on Pinterest
Peter Finch/Getty Images

Thyroid cancer develops in the thyroid when abnormal cells begin to grow uncontrollably. According to the American Cancer Society (ACS), types of thyroid cancer vary depending on which cells the cancer develops in.

The two main types of thyroid cells in which cancer can develop are follicular cells and C cells. Some people may also refer to C cells as parafollicular cells. There are also less common cells in the thyroid gland, which include immune system and supportive cells.

Different cancers can develop from each kind of cell. The differences are important, as this can suggest the severity of cancer and why type of treatment is necessary.

Types of thyroid cancer fall into three main categories:

  • differentiated
  • anaplastic
  • medullary

As with many cancers, there are four stages to thyroid cancer, running from stages 1 to 4.

Classifying which stage the cancer is in depends on the following:

  • size of the tumor
  • whether the cancer has spread into the surrounding lymph nodes
  • whether the cancer has spread to the organs further away

Stage 1 is the earliest stage. Severity increases with each stage until stage 4, at which point the cancer has spread the furthest.

It is also worth noting that with differentiated thyroid cancer (papillary or follicular), age also plays a role in the staging. Doctors do not classify people younger than 55 with differentiated thyroid cancer as stage 3 or 4 because this group is less likely to pass away from this form of cancer.

General symptoms of thyroid cancer can include:

  • pain and swelling in the neck
  • hoarseness
  • difficulty swallowing
  • difficulty speaking
  • difficulty breathing
  • weight loss
  • fatigue

However, people can experience symptoms in different ways depending on the individual and the type of cancer. For example, medullary thyroid cancer can cause additional gastrointestinal symptoms, such as diarrhea or constipation.

Metastasis is where the cancer has spread from the thyroid to organs further off. This can be difficult to identify without clinical testing. However, metastatic thyroid cancer can cause signs such as:

  • cancerous lumps in the neck
  • pulmonary symptoms if the cancer has spread to the lungs
  • fracture in the bones of the spine or hips

As mentioned, there are two main cell types from which thyroid cancer can develop. These are follicular and C cells. The type of thyroid cancer depends largely on which group of cells it stems from.

Follicular cells are the cells that control metabolism from the thyroid. They do this by using iodine in the blood to produce thyroid hormones. Cancer that develops from the follicular cells are typically the differentiated type but can also be anaplastic.

Differentiated cancers that can develop from the follicular cells include:

  • papillary cancer
  • follicular cancer
  • Hürthle cell cancer

Anaplastic thyroid cancer is uncommon, but very aggressive and difficult to treat.

C cells are the other thyroid cells in which cancer can develop. These cells control the way the body uses calcium. They do this by producing calcitonin hormones.

C cells produce medullary thyroid cancers. These are less common than the differentiated types, and are both harder to identify and treat.

There are two types of medullary thyroid cancer: sporadic and familial. Most cases occur in younger people and are sporadic, where the cancer does not run in the family, leaving around 25% of cases familial.

Causes of thyroid cancer are often unclear. However, a combination of genetic conditions and risk factors can increase the likelihood of a person developing the condition.

According to research in the International Journal of Cancer, the presence of certain risk factors in certain regions causes there to be more cases of thyroid cancer in some countries than others. Risk factors are likely to include:

  • excessively high or low iodine intake
  • consuming a diet that is low in vegetables
  • exposure to ionizing radiation

Other sources also suggest the following risk factors:

  • Age: Typically, the risk of thyroid cancer may increase as people get older, however, it also often occurs in younger ages.
  • Gender: Evidence also suggests that thyroid cancers are more common in women.
  • Radiation: Exposure from medical radiation, such as from diagnostic procedures, can increase the risk of thyroid cancer.

Research also suggests a person is more likely to develop thyroid cancer if they are overweight.

When diagnosing thyroid cancer, a doctor will usually begin by looking over a person’s medical history and conducting a physical examination. They will then typically use a form of imaging test, such as an ultrasound or MRI, to assess areas that may contain cancerous cells.

A doctor is also likely to suggest a biopsy, where they remove a sample of cells from the area and send them on to a laboratory from analysis. Blood testing can also support the diagnosis, as a doctor can compare hormone levels to check how well the thyroid is functioning.

There are different treatment options available for differentiated and undifferentiated thyroid cancer. How appropriate each form of therapy is will depend on the stage and type of thyroid cancer a person has.

The goal of treatment is to cure the condition by getting rid of the cancer completely or increasing a person’s prognosis by removing as much cancer as possible.

Currently, standard treatment for thyroid cancer involves:

  • surgery, such as a lobectomy, thyroidectomy, or tracheostomy
  • radiation therapy, which includes radioactive iodine therapy
  • chemotherapy
  • thyroid hormone therapy
  • targeted therapy, which uses drugs such as tyrosine and protein kinase inhibitors
  • watchful waiting

People often use a combination of techniques when treating thyroid cancer.

There are also ongoing trials for immunotherapy as a treatment option. This is a method that uses the body’s immune system to fight cancer.

A person should thoroughly discuss their options with a healthcare professional before making a decision to ensure they are confident in their choice of treatment plan.

It is not always possible to prevent thyroid cancer. However, a person can significantly reduce the chances of developing the condition by avoiding risk factors. For example, it is a good idea to minimize exposure to radiation and to maintain a moderate body weight.

Thyroid cancer is often curable, depending on the type of cancer, the age when a person receives a diagnosis, and which stage it is in when the person begins treatment.

The ACS suggest that a relative 5-year survival rate for a person with thyroid cancer is 90%. This means that most people who have thyroid cancer survive for at least 5 years after their diagnosis.

The thyroid gland is responsible for regulating different body functions, including metabolism and body temperature.

Cancer can affect the thyroid by developing from cells present in the thyroid. The main group of cells cancer affects in the thyroid are the follicular cells and C cells.

As research is still unclear on potential risk factors, it is advisable for people to regularly get nodules checked out early and talk with their doctor about new or worsening symptoms. They can also enquire about genetic testing if at risk for familial cancer.

Thyroid cancer is curable depending on which stage the cancer is in when the person receives treatment. Therefore, it is important to try and catch it early.