Thyroid cancer occurs when cells in the thyroid become abnormal and grow out of control. The thyroid gland is located in front of the neck and produces thyroid hormone which helps regulate metabolism, heart rate, blood pressure, and body temperature.
There are different types of thyroid cancer.
Differentiated thyroid cancers are the most common types of thyroid cancer. There are three main types of differentiated thyroid cancer:
- Papillary
- Follicular
- Second-most common differentiated thyroid cancer
- Accounts for about 10% thyroid cancers
- More common in countries where people don’t get enough iodine in the diet
- Does not spread to lymph nodes, but can spread to other parts of the body, such as the lungs or bones
- The prognosis is very good in most cases
- Hürthle cell
- Accounts for about 3% of thyroid cancers
- Harder to find and to treat
Other types of thyroid cancers include:
- Medullary thyroid cancer (MTC)
- More difficult to find and treat
- Sporadic MTC
- Familial MTC
- More difficult to find and treat
- Anaplastic (also called undifferentiated carcinoma)
- Rare and aggressive form of thyroid cancer
- Accounts for about 2% of all thyroid cancers
- May develop from an existing papillary or follicular cancer
- Thyroid lymphomas, thyroid sarcomas, or other rare tumors account for less than 4% of thyroid cancers
What Are Symptoms of Differentiated Thyroid Cancer?
Thyroid cancer may have no early signs and symptoms. When symptoms of thyroid cancer occur, they may include:
- Growth (nodule) on the neck that may grow slowly or quickly
- Pain in the front of the neck, that may go up to the ears
- Hoarseness, voice changes, or inability to speak
- Swelling in the neck
- Difficulty breathing
- Problems swallowing
- Cough (may include coughing up blood)
What Causes Differentiated Thyroid Cancer?
The cause of thyroid cancer is not known but it is linked with several genetic (inherited) conditions.
Risk factors for thyroid cancers include:
- Genetic conditions
- Carney complex, type I
- Cowden disease
- Familial adenomatous polyposis (FAP)
- Familial nonmedullary thyroid carcinoma
- Female gender
- Three times common in women than in men
- Age
- Women are usually in their 40s or 50s when diagnosed and men are usually in their 60s or 70s
- Family history of thyroid cancer
- Radiation exposure
- Certain medical treatments
- Radiation fallout from power plant accidents or nuclear weapons
- Overweight or obesity
- Low iodine in the diet
- More common in other parts of the world; most people in the U.S. get enough iodine in the diet
How Is Differentiated Thyroid Cancer Diagnosed?
Thyroid cancer is diagnosed with a history and physical examination. If a growth on the thyroid gland is seen or felt, tests may include:
- Imaging tests
- Chest X-ray
- Computed tomography (CT) scan
- Magnetic resonance imaging (MRI) scan
- Positron emission tomography (PET) scan
- Radioiodine scans
- Ultrasound
- Fine needle aspiration biopsy
- Blood tests
- Thyroid-stimulating hormone (TSH)
- T3 and T4 (thyroid hormones)
- Thyroglobulin
- Calcitonin
- Carcinoembryonic antigen (CEA)
- Complete blood count (CBC)
- Tests for bleeding disorders
- Liver and kidney function tests
What Is the Treatment for Differentiated Thyroid Cancer?
Treatment for thyroid cancer involves one or more of the following:
- Surgery to remove the cancer
- Radioactive iodine (“radioiodine therapy”)
- Thyroid hormone
- External-beam radiation therapy
- Chemotherapy
From 
https://www.uptodate.com/contents/thyroid-cancer-the-basics?search=Thyroid%20Cancer&source=search_result&selectedTitle=1~150&usage_type=default&display_rank=1
https://www.cancer.org/cancer/thyroid-cancer.html