What is Thyroid Cancer? What are the Symptoms of Thyroid Cancer?

Thyroid cancer is an uncontrolled cell growth that starts in the thyroid gland and has many types. While most types grow slowly, some can be aggressive. This type of cancer may not cause any symptoms in its early stages; however, as the cancerous tissue grows, it can lead to symptoms such as swelling in the neck, changes in voice, and difficulty swallowing. Thyroid cancers account for approximately 1% of all cancers【1】. In recent years, the incidence has increased particularly among the female population. Imaging methods may be used during the diagnosis stage. Most thyroid cancers can be treated with various procedures, and the types of cancer that respond best to treatment are small tumors in the early stages.

What is Thyroid Cancer?

The thyroid is a butterfly-shaped gland located in the right and left lobes of the trachea at the base of the throat. The thyroid gland cannot be felt through the skin. It is responsible for the production and secretion of various hormones, which affect digestion, heart function, and muscle function. These hormones also have important roles in energy production, heat production, oxygen consumption, and metabolism control. Thyroid cancer develops when the cells in the thyroid tissue change or mutate. Abnormal cells begin to multiply in the thyroid, leading to the formation of tumors when a certain number is reached. Thyroid cancer has four main types: papillary thyroid cancer, follicular thyroid cancer, medullary cancer, and anaplastic thyroid cancer.

What are the Symptoms of Thyroid Cancer?

Patients with thyroid cancer may not show any symptoms in the early stages. The tumor structure may be accidentally discovered during imaging methods performed for other reasons. Thyroid nodules can be a sign of cancer, but they are mostly benign formations. As thyroid cancer grows, it may show the following symptoms:

• A lump or lumps in the neck that can be felt by touch
• Changes in the patient’s voice, including increased hoarseness
• Difficulty swallowing and pain while swallowing
• Difficulty breathing
• Swelling of lymph nodes
• Pain in the neck and throat area
• A feeling of pressure in the front of the neck
• Fatigue
• Loss of appetite
• Coughing
• Diarrhea
• A red face
• Nausea and vomiting
• Unexplained weight loss

What Causes Thyroid Cancer?

The incidence of thyroid cancer has tripled in the last 30 years. It is known to be the fifth most common cancer among women. The two most significant factors known to cause thyroid cancer are family history and exposure to ionizing radiation. Ionizing radiation can lead to DNA breaks and mutations in body cells. Therefore, mutated thyroid cells can undergo abnormal growth, resulting in tumor formation. Another reason is family history. If two or more people in a family are affected by thyroid cancer, it can be suspected that the disease is hereditary. Other causes of thyroid cancer can be briefly summarized as follows:

• Obesity
• Diabetes
• Lifestyle
• Being female
• Late onset of menopause
• Previous breast, esophagus, or testicular cancer
• Genetic mutations causing endocrine diseases
• Thyroid gland inflammation (thyroiditis)
• Exposure to radioactive fallout due to nuclear disasters
• Having undergone cancer or acne treatment in childhood
• Having received radiation therapy due to the thymus
• Being aged 65 or older or under 20
• Exposure to endocrine-disrupting chemicals
• Iodine deficiency or excess
• A history of goiter

Stages of Thyroid Cancer

Doctors may use various tests and procedures to determine the size of thyroid cancer and stage the cancer. The information obtained through these diagnostic methods is interpreted and used. Determining the stage of cancer provides information about the course of the disease and helps define the treatment plan. Staging is also used to determine whether the cancer has spread and, if so, how far it has spread. Thyroid cancer stages are classified as I, II, III, and IV. Lower numbers indicate a higher likelihood of a positive response to treatment and that the cancer is confined to the thyroid. Higher numbers suggest a more serious condition, indicating that the cancer may have spread to other tissues in the body. Stages may vary depending on the type of cancer.

How is Thyroid Cancer Diagnosed?

There are many tests and procedures used to diagnose thyroid cancer. These tests aim to examine the thyroid gland, neck, and blood values. The first step in diagnosis can be a physical examination and learning about the medical history. A general physical examination of the body can be performed to check for signs such as swelling in the neck, throat, and lymph nodes, as well as other unusual conditions. Understanding the patient's previous illnesses and treatment histories can also be beneficial during the diagnosis. Other diagnostic methods can be briefly described as follows:

• Thyroid Function Blood Tests: Tests that measure the blood levels of thyroid-stimulating hormone (TSH) and other hormones produced by the thyroid gland can assist in cancer diagnosis.
• Laryngoscopy: This method involves examining the larynx with a camera and a thin tube. Thyroid cancer can press on the larynx and vocal cords, and laryngoscopy helps visualize whether the vocal cords are moving normally.
• Ultrasound Examination: High-energy sound waves create images of the internal tissues of the neck. This method provides information about the size and location of the thyroid tumor. Computed tomography and similar imaging methods may also be used.
• Genetic Testing: Some thyroid cancers are caused by hereditary genes that can be passed from parents to children. Genetic tests can be conducted after consulting with a genetic counselor.
• Radioactive Iodine Scanning: A radioactive form of iodine and a special camera for imaging may be used to detect cancer cells present in the body. When radioactive iodine is injected into the bloodstream, thyroid cells absorb it. Areas showing less radioactivity are thought to contain cancerous tissue.
• Fine Needle Aspiration Biopsy of the Thyroid: Samples are taken from different parts of the thyroid tissue using a thin needle. The tissue samples are examined by a pathologist to diagnose the type of cancer.
• Surgical Biopsy: A surgical procedure is performed to remove a thyroid nodule or part of the thyroid gland. Cells and tissues are examined by a pathologist.

How is Thyroid Cancer Treated?

The treatment for thyroid cancer may vary depending on the type of cancer, its stage, and the patient's overall health. Most patients undergo a combination of treatments, including surgery, thyroid hormone replacement therapy, radioactive iodine therapy, radiotherapy, and chemotherapy. The treatment methods for thyroid cancer can be briefly described as follows:

• Surgery: This is the most commonly used treatment procedure. Depending on the location and size of the tumor, it may involve the complete removal of the thyroid gland (thyroidectomy) or a portion of it (lobectomy). If cancer cells have spread, lymph nodes may also be removed.
• Radioiodine Therapy: This requires a higher dose than that used for diagnostic purposes. Radioiodine reduces and destroys cancerous thyroid cells. This treatment is considered reliable, as nearly all of the radioiodine is absorbed by the thyroid gland, leaving minimal levels in the body.
• Chemotherapy: Chemotherapeutic drugs are administered intravenously or orally. These drugs kill cancer cells, preventing the growth and spread of cancer.
• Thyroid Hormone Replacement Therapy: After surgery, thyroid hormones that the body cannot produce are replaced. This may involve prescription pills that need to be taken daily.
• Radiotherapy: Radiation therapy may be used to kill cancer cells or stop their growth. High-energy rays such as X-rays and protons can be utilized in this method. Radiotherapy can be applied when cancer does not respond to treatment or recurs.
• Targeted Drug Therapy: Medications that focus on the chemicals present in cancer cells, aiming to destroy only the cancerous cells, may also be preferred in treatment.

Cancer, regardless of its type, is a frightening disease. However, early diagnosis can ensure the successful treatment of thyroid cancer. Therefore, it is essential to be well-informed about the symptoms and to have regular health check-ups. Additionally, individuals with a family history of thyroid cancer or other thyroid diseases are advised to see a doctor regularly. If you or someone close to you is experiencing symptoms of thyroid cancer, it is recommended to consult a physician as soon as possible.