Table Of Content

Introduction

Thyroid cancer begins when the cells in the thyroid undergo abnormal multiplication and division. The thyroid is a butterfly-shaped gland situated in the front part at the base of the neck, below the thyroid cartilage (Adam's apple). The thyroid gland is responsible for the production of hormones that help in regulating the heart rate, body temperature, blood pressure, metabolism, and body weight.

How Does Thyroid Cancer Develop?

Thyroid cancer develops as a result of changes occurring in the DNA of the thyroid cells. These changes or mutations in the cell's DNA lead to their abnormal proliferation.

Types of Thyroid Cancer

Thyroid cancers are classified into various types depending on the types of cells that are found in the cancer. There are three types of thyroid cancer. They are:

1. Differentiated thyroid cancers: These are the cancers that occur in the follicular cells, responsible for the production and storage of thyroid hormone. Differentiated thyroid cancer cells appear similar to healthy cells when viewed under a microscope.

  • Papillary thyroid cancer: This cancer usually grows slowly and develops in one lobe of the thyroid gland, but it might affect both lobes sometimes. It is a very common type of thyroid cancer that can happen to anyone at any age. However, it most often affects people between 30 to 50 of age. Although papillary thyroid cancer is slow growing, it might often spread to the lymph nodes in the neck. However, if detected early, it is highly treatable and curable. Papillary thyroid cancer is otherwise also called papillary carcinomas or papillary adenocarcinomas
  • Follicular thyroid cancer: This is cancer that is usually found in people aged above 50. It is a rare cancer that does not usually spread into the lymph nodes. However, follicular cancer can spread into other parts of the body, like the lungs or the bones. Follicular thyroid cancer is otherwise also known as follicular carcinoma or follicular adenocarcinoma.
  • Hurthle cell thyroid cancer: This is a rare type of thyroid cancer in which cancer cells may grow aggressively and spread into the neck and other parts of the body. This cancer is otherwise also known as oxyphilic cell carcinoma.

2. Medullary thyroid cancer: This is a very rare type of thyroid cancer that occurs in the C cells of the thyroid. The C cells of the thyroid gland are responsible for making
the calcitonin hormone that helps control the amount of calcium in the blood. High levels of calcitonin in the body can be a sign of medullary thyroid cancer in its early stages. Certain medullary thyroid cancers are caused due to changes in the RET gene that are usually passed from parents to children. This cancer can spread to lymph nodes and other organs like the lungs or liver. Medullary thyroid cancer, also known as Medullary thyroid carcinoma, is usually difficult to detect and treat. There are two types of Medullary thyroid cancer. They are:

  • Sporadic Medullary thyroid cancer: This type is not an inherited one and can occur in adult patients in only one lobe.
  • Familial Medullary thyroid cancer: This cancer type is an inherited condition, and also a subtype of a hereditary endocrine cancer syndrome called multiple endocrine neoplasia type 2 (MEN2).

3. Anaplastic thyroid cancer: This cancer is a rare and aggressive type that usually grows and spreads quickly into the surrounding lymph nodes, tissues, and organs. Anaplastic thyroid cancer is otherwise also known as Anaplastic carcinoma or undifferentiated carcinoma. This cancer is given the name undifferentiated as the cancer cells here are not like normal thyroid cells. This cancer is usually difficult to treat.

Stages of Thyroid Cancer

The various stages are based on which the doctor determines the progress, prognosis, and treatment of thyroid cancer. Since papillary and follicular thyroid cancers come under the category of differentiated thyroid cancer, their staging is the same. The staging of thyroid cancer is divided based on thyroid cancer occurring in patients below 55 years of age and patients about 55 years of age.

Staging of thyroid cancer in patients below 55 years of age:

It has two stages:

Stage I: In this stage, the thyroid cancer may or may not have spread to the surrounding lymph nodes and can be of any size. The tumor here has not spread into distant Parts of the body

Stage II: In this stage, thyroid cancer has spread into other parts of the body, like the distant lymph nodes, lungs, or bones.

Staging of thyroid cancer (papillary and follicular) in patients above 55 years of age:

It is divided into four stages:

Stage I: In this stage, a tumor of 4 centimeters or less is found in the thyroid.

Stage II: In this stage, one of the following is found,

  • The tumor is 4 cm or smaller, and cancer has spread into the surrounding lymph nodes
  • The tumor is more than 4 cm in size and may have spread into the surrounding lymph nodes.
  • The tumor is of any size, and cancer has spread into the surrounding neck muscles from the thyroid and may have also spread into the surrounding lymph nodes.

Stage III: In this stage, the tumor is of any size, and cancer here may have spread to the lymph nodes, beyond the thyroid into the soft tissues under the skin, the esophagus, the larynx, the recurrent laryngeal nerve, or the trachea.

Stage IV: This stage is further divided into 2 stages. They are,

  • Stage IVA: In this stage, the tumor is of any size and has spread into the surrounding structures like the front area of the spine or blood vessels between the lungs. Cancer in this stage may have also spread into the lymph nodes.
  • Stage IVB: In this stage, the tumor is of any size, very advanced, and has spread beyond the thyroid into other body parts like the lungs and bones.

Stages of Anaplastic thyroid cancer (for patients of all age groups):

Anaplastic thyroid cancer is a type of cancer that quickly grows. This cancer has usually spread within the neck when it is diagnosed, and it is considered stage 4 of thyroid cancer. This cancer is divided into the following stages:

Stage IVA: In this stage of anaplastic thyroid cancer, the tumor may be of any size and is present only in the thyroid.

Stage IVB: In this stage, cancer found will be of any one of the following,

  • The tumor is of any size, and the cancer here has spread to the lymph nodes
  • The tumor is of any size, and cancer has spread into the surrounding neck muscles from the thyroid and may have also spread into the surrounding lymph nodes
  • The tumor is of any size, and cancer here may have spread to the lymph nodes. Here, the cancer has spread beyond the thyroid into the soft tissues under the skin, the esophagus, the larynx, the recurrent laryngeal nerve, or the trachea.

Stage IVC: The tumor is of any size, very advanced, and has spread beyond the thyroid into other body parts like the lungs and bones.

Stages of Medullary thyroid cancer (for patients of all age groups):

Stage I: In this stage, a tumor of 2 cm or less is found. The cancer is present only in the thyroid.

Stage II: In this stage, one of the following is seen,

  • The size of the tumor is more than 2cm, and the cancer is found only in the thyroid
  • The tumor is of any size, and cancer has spread into the surrounding neck muscles.'

Stage III: In this stage, the tumor is of any size. Cancer in this stage might have spread into the neck muscles, lymph nodes on either one or both sides of the larynx, or trachea from the thyroid.

Stage IV: In this stage, the cancer staging is divided into the following substages,

  • Stage IVA: In this stage, one of the following is found,
    ▪ The tumor is of any size, and cancer here may have spread to the lymph nodes. Here the cancer has spread beyond the thyroid into the soft tissues under the skin, the esophagus, the larynx, the recurrent laryngeal nerve, or the trachea.
    ▪ Cancer in this stage might have spread into the neck muscles and lymph nodes on either one or both sides.
  • Stage IVB: In this stage, the tumor is of any size, and cancer has spread from the thyroid into the front portion of the spine or the spine. It may have also spread into the lymph nodes, carotid artery, or the blood vessels in the spaces between the lungs.
  • Stage IVC: In this stage, the tumor is of any size, and cancer has spread from the thyroid into the other body parts like the liver or lungs.

Causes & Risk Factors of Thyroid Cancer

Thyroid cancer develops as a result of changes occurring in the DNA of the thyroid cells. These changes or mutations in the cell's DNA lead to their abnormal proliferation. It is not known as to what causes thyroid cancer. However, there are certain factors that might increase a person's risk of developing thyroid cancer. These risk factors are:

  • Family history: people having a family history of thyroid cancer are at high risk.
  • Age and gender: The risk of developing thyroid cancer is high in women when compared to men. Although thyroid cancer can happen at any age, women between 40 and 50 are more prone to developing it, whereas men usually develop thyroid cancer in their 60s or 70s.
  • Radiation exposure: One of the proven risk factors for thyroid cancer development is exposure to radiation. Head and neck radiation treatment and exposure to radiation due to radiation fallouts are some factors that contribute to the risk of developing thyroid cancer.
  • Genetic conditions: People with inherited conditions like Familial adenomatous polyposis (FAP), Familial medullary thyroid carcinoma, Carney complex, type I, or Cowden disease are at a high risk of getting thyroid cancer.
  • Iodine deficiency: People who do not consume enough iodine and lack it in their bodies risk developing thyroid cancer.
  • Obesity: People who are overweight or have obesity are at more risk of getting thyroid cancer.

Symptoms of Thyroid Cancer

In most cases, people having thyroid cancer don't even know about it. This is because there are no prominent symptoms in the early stages of thyroid cancer. In certain instances, thyroid cancers are detected during a physical examination. The signs and symptoms of thyroid cancer appear and become prominent as the cancer grows. The symptoms of thyroid cancer include:

  • A nodule or lump in the neck
  • Difficulty breathing and swallowing
  • Pain while swallowing
  • Persistent cough
  • Pain in the neck and throat
  • Voice changes and hoarseness

Thyroid Cancer Screening

There is no standard screening test that can be used for the early detection of thyroid cancer. In certain instances, thyroid cancer without symptoms might be found during regular physical examination, where the doctor examines the patient's neck for lumps or swelling or during surgery or an ultrasound done for some other condition.

Diagnosis of Thyroid Cancer

There are various tests that can be performed to diagnose thyroid cancer. These tests for thyroid cancer include:

  • Medical history and physical examination: Upon noticing any symptoms that might suggest the possibility of thyroid cancer, your doctor will ask you for your complete medical history and will perform a detailed physical examination in order to assess the possible risk factors, symptoms, or any other health issue you have.
  • Blood test: It is performed to assess the levels of hormones in the body and to check if the thyroid is functioning properly.
  • Fine-needle aspiration biopsy of the thyroid: In this test, using a thin needle that is inserted into the thyroid, various samples of the thyroid tissues are removed from several different thyroid parts. The tissues are then assessed under a microscope to check for cancer cells.
  • Surgical biopsy: In this, the thyroid nodule or one lobe of the thyroid is removed during surgery, and the cells and the tissues are then viewed under a microscope to examine for signs of cancer.
  • Imaging tests: Various imaging tests like ultrasound, radioiodine scan, chest X-ray, CT scan, MRI scan, and pet scan can be done to check for thyroid cancer.
  • Laryngoscopy: In this test procedure, the doctor examines the larynx (voice box) with a laryngoscope. In certain instances, the thyroid tumor may press and affect the vocal cords. A laryngoscopy is performed to check if the vocal cords are moving normally.

Treatment of Thyroid Cancer

Depending on the individual's overall health, the type and size of cancer, and the patient's preference, the doctor may recommend treatment options. The various treatment options available to treat thyroid cancer include surgery, radioiodine therapy, radiation therapy, chemotherapy, immunotherapy, and targeted drug therapy. You may receive one or a combination of these treatment types if you have thyroid cancer.

Surgery: Surgery is the most common treatment approach used for thyroid cancer. There are various types of surgeries that might be performed on a patient having thyroid cancer. These surgeries include,

  • Lobectomy: It is a surgery where the doctor removes cancer containing lobe along with the isthmus.
  • Thyroidectomy: In this surgery, a doctor either removes all but a little part of the thyroid gland (called near-total thyroidectomy) or the doctor removes the entire thyroid gland (called a total thyroidectomy).
  • Lymph node removal: If cancer has spread into the surrounding lymph nodes, then these cancer-affected lymph nodes will also be removed during the surgery performed on the thyroid.

Radioactive Iodine therapy: In this treatment method, the patients are asked to swallow a pill or liquid containing a high dose of radioactive Iodine. This radioactive iodine shrinks and destroys cancer cells. Radioiodine therapy or radioactive iodine therapy can also be used to destroy any thyroid tissue that was not removed during surgery or treat certain types of thyroid cancer that might have spread into the lymph nodes and other surrounding body parts.

Radiation therapy involves using high beams of X-rays or protons that are targeted toward the cancer cells to destroy them. External beam Radiation therapy is usually used to treat thyroid cancers that have spread beyond the thyroid gland or do not take up iodine. Radiation therapy may also be used to treat cancer or lower the risk of its reference post-surgery.

Chemotherapy treatment involves using medications that destroy the cancer cell. This treatment for treating thyroid cancer can be given alone or in combination with other cancer treatments. The effectiveness of radiation therapy is often increased by chemotherapy, and hence the two are usually given in combination.
In thyroid cancer, chemotherapy is rarely used. Chemotherapy is used for treating anaplastic thyroid cancer in combination with external beam radiation therapy and is sometimes also used to treat advanced cancers that are not responding to any other treatment.

Targeted Drug Therapy: In this treatment approach, medications are used to specifically identify and target cancer cells without causing damage to the healthy cells. These medications are targeted toward the proteins that help the cancer cells to grow and spread.

Hormone treatment is usually given to patients who have undergone surgery in order to replace the hormone that is needed in the body. The hormone treatment might also help in slowing down the growth of any differentiative cancer cells left behind. Levothyroxine is used as thyroid hormone replacement in hormone treatment.

Prognosis of thyroid cancer

The prognosis of thyroid cancer depends on the following,

  • Age
  • Overall patient health and response to the treatment
  • Recurrence of cancer after its treatment
  • Cancer stage
  • Stage of diagnosis of the cancer

For various types of thyroid cancers, the five-year survival rate differs. The survival rates for different thyroid cancers include,

  • Papillary thyroid cancer: Localised cancer 100%, metastasized cancer 80%.
  • Follicular thyroid cancer: Localised cancer 100%, metastasized cancer 63%.
  • Medullary thyroid cancer: Localised cancer 100%, metastasized cancer 40%.
  • Anaplastic thyroid cancer: Localised cancer around 31%, metastasized cancer 4%.

Prevention of Thyroid Cancer

The following preventive measures can be used to reduce the risk of developing thyroid cancers.

  • Prophylactic surgery: A preventive surgery can be done to remove the thyroid upon finding a mutated or altered gene in genetic tests, to prevent it from increasing the risk of thyroid cancer.
  • Reducing radiation exposure: Childhood exposure to radiation is a known risk factor for thyroid cancer. This can be reduced by lowering the doses of radiation in children during imaging tests.

Thyroid Cancer FAQs

1. Is thyroid cancer treatable?

When detected early and treated on time, thyroid cancer is highly treatable, and, in some cases, it can also be cured totally.

2. I have an iodine deficiency. Will I get cancer?

Iodine deficiency is a risk factor for getting thyroid cancer. However, it is essential to not panic and consult your doctor and raise any concerns you have if you are iodine deficient.

3. I have a lump in my neck. Does it mean I have thyroid cancer?

No, a lump in the neck does not always have to be thyroid cancer. However, it is better to not ignore the lump and get it checked by your doctor as it might be a sign of thyroid cancer.

4. What are the signs and symptoms of thyroid cancer to watch out for?

Look out for the following signs and symptoms of thyroid cancer:

  • A nodule or lump in the neck
  • Difficulty breathing and swallowing
  • Pain while swallowing
  • Persistent cough
  • Pain in the neck and throat
  • Voice changes and hoarseness

5. Why has my doctor prescribed me levothyroxine?

After undergoing a surgery for thyroid cancer treatment, the doctor prescribes levothyroxine as thyroid hormone replacement for the natural hormone needed by the body.

6. What is hormone treatment in thyroid cancer?

Hormone treatment is usually given to patients who have undergone surgery in order to replace the hormone that is needed in the body. The hormone treatment might also help in slowing down the growth of any differentiative cancer cells left behind. Levothyroxine is used as thyroid hormone replacement in hormone treatment.

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