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 80-90% of thyroid cancer cases are papillary cancer. Papillary cancer can spread to the lymph nodes in the neck, and in rare cases to the lungs. 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. Women are three times more likely than men to have papillary thyroid cancer.
Risk factors for papillary thyroid cancer include:
- A family history of thyroid cancer
- Radiation exposure to the head, throat, and neck
Follicular Thyroid Cancer
Follicular thyroid cancer accounts for approximately 5 to 10% 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. It is rare but possible for follicular cancer to spread through the bloodstream and invade distant organs or bones. Overall, follicular cancer is not common. Most patients diagnosed with follicular thyroid cancer are between ages 40 and 60 years.
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
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. 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. This test is sometimes unable to accurately diagnose thyroid cancer.
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).