In cancer terminology, "well-differentiated" means the cancer cells resemble the normal cells from which they grew. Well-differentiated cancers grow more slowly and have a better prognosis than undifferentiated cancers, which are more aggressive and have poorer outcomes.
Papillary and follicular thyroid cancers are considered well-differentiated cancers.
Papillary Thyroid Cancer
Papillary thyroid cancer is the most prevalent type of thyroid cancer--with over 50,000 new cases per year in the United States. Around 80% of thyroid cancer cases are papillary cancer. Papillary cancer can spread to the lymph nodes and surrounding structures. About 20-40% of patients diagnosed with papillary thyroid cancer will have involved lymph nodes. Fortunately, papillary thyroid cancer is the most treatable type of thyroid cancer. Many patients with papillary thyroid cancer have good outcomes if they are diagnosed early and receive treatment.
Risk factors for papillary thyroid cancer include:
- A family history of thyroid cancer
- Radiation exposure to the head, throat, and neck
- Being less than 20 years old
Follicular Thyroid Cancer
Follicular thyroid cancer accounts for approximately 10 to 15% of all diagnosed thyroid cancers. Many patients with follicular thyroid cancer can be cured with early detection and appropriate treatment. Younger patients have higher cure rates. Follicular cancer can spread through the bloodstream and invade distant organs or bones. It also often invades veins and arteries. Overall, follicular cancer is not common. Most patients diagnosed with follicular thyroid cancer are between ages 40 and 60 years. Women are three times more likely to get it than men.
Signs and Symptoms
Many patients with papillary and follicular thyroid cancer do not show symptoms. Patients typically seek medical attention when they could see or feel a mass or lump (nodule) on the neck. Masses that are solid, firm, and growing larger are of greater concern for cancer.
Some patients with these thyroid nodules may notice:
- Difficulty swallowing
- Shortness of breath when laying down
- Pain in the neck, jaw, or ears (rare)
If a thyroid nodule is suspected, your physician will review your medical and family history. The majority of patients diagnosed with papillary thyroid cancer have normal thyroid function. Patients with an overactive thyroid function (“hyperthyroid”) usually do not have cancer. Those with underactive function (“hypothyroid”) are slightly more likely to have cancer.
If thyroid cancer is suspected, the following diagnostic tests may be ordered:
Blood tests help show if your thyroid is functioning normally. Tests commonly ordered check levels of thyroid-stimulating hormone (TSH) and T3 and T4 hormones. Blood tests are also used to monitor thyroid cancers.
Fine-needle aspiration biopsy (FNAB) is the most useful test for determining if a thyroid mass is cancerous or not, and it has a 97% accuracy rate. This simple outpatient procedure involves a small needle injected into the mass or nodule. The needle removes cells that will be examined in the lab under a microscope.
Advanced imaging scans of your neck help your physician see the precise location and extent of the suspected cancer. Some of these include: Ultrasound scan (does not involve radiation), Computed tomography (CT) scan, and Magnetic resonance imaging (MRI).