The Basics of Follicular Thyroid Cancer
What is Follicular Thyroid Cancer?
Follicular thyroid cancer (FTC), also known as follicular thyroid carcinoma, is a type of thyroid cancer that originates from the thyroid gland’s follicular cells, which produce and store thyroid hormones. Though not as common as papillary thyroid cancer, FTC accounts for about 10-15% of all thyroid cancer cases. FTC is relatively more aggressive than papillary thyroid cancer but less so than anaplastic thyroid cancer.
Prevalence of Follicular Thyroid Cancer
FTC primarily affects adults, with a higher incidence in women than in men, at a ratio of approximately 3:1. The peak age of onset is between 40 and 60 years. Geographically, FTC is more prevalent in regions with iodine deficiency, although this has decreased with improved iodine supplementation in many parts of the world.
Types of Follicular Thyroid Cancer
There isn’t a single subclassification for follicular thyroid cancer. However, it can be categorized based on its growth pattern and cellular features. These variants can influence a patient’s prognosis and treatment approach. Here are some examples:
- Minimally invasive follicular thyroid carcinoma (MIFTC): This is a less aggressive form that tends to stay confined to the thyroid gland.
- Follicular thyroid carcinoma with vascular invasion (FVCI): This variant shows invasion of blood vessels, increasing the risk of spreading to other parts of the body.
- Hürthle cell carcinoma: This is a type of follicular thyroid cancer that arises from Hürthle cells, a different kind of follicular cell.
Follicular vs. Papillary Thyroid Cancer
Like papillary thyroid cancer, follicular thyroid cancer is well-differentiated. This means that these cancers resemble normal thyroid tissue under a microscope. However, they have some key differences:
- Cell origin: Both arise from follicular cells, but papillary thyroid cancer (PTC) typically presents with a papillary arrangement of cells (meaning the cells form finger-like protrusions), whereas FTC does not.
- Spread: PTC often spreads to lymph nodes, whereas FTC is more likely to invade blood vessels and spread (metastasize) through the bloodstream to distant organs such as lungs and bones.
- Prognosis: PTC generally has a better prognosis than FTC, especially in younger patients.
Risk Factors
Genetic Predispositions
Genetics play a crucial role in the development of follicular thyroid cancer. Mutations in certain genes, such as RAS, PAX8-PPARγ, and TERT promoter mutations, have been implicated in its pathogenesis. Individuals with familial syndromes like Cowden syndrome or familial adenomatous polyposis (FAP) are at higher risk.
Radiation Exposure
Exposure to radiation, particularly during childhood, significantly increases the risk of developing thyroid cancers, including FTC. Environmental radiation sources can include radiation therapy for other cancers or nuclear accidents.
Symptoms and Early Warning Signs
Common Symptoms
Early-stage follicular thyroid cancer often presents with few or no symptoms. However, as the cancer progresses, the following symptoms may emerge:
- A painless lump or nodule in the neck
- Difficulty swallowing
- Hoarseness or changes in voice
- Persistent cough not associated with a cold
Advanced Symptoms
If the cancer has spread to other parts of the body, additional symptoms may include:
- Bone pain
- Respiratory difficulties if metastasized to the lungs
- Fatigue and general malaise
When to See a Doctor
It’s crucial to consult a healthcare provider if you experience any persistent symptoms such as a neck lump, changes in voice, or difficulty swallowing. Early detection can significantly improve treatment outcomes.
Diagnosis
Physical Examination
A thorough physical examination by a healthcare professional is the first step in diagnosing follicular thyroid cancer. This includes the palpation of the thyroid area to check for nodules.
Imaging Tests
Several imaging tests are utilized to assess the thyroid gland and detect potential cancer.
- An ultrasound is a first-line imaging procedure used to visualize the thyroid gland and assess the characteristics of any detected nodules.
- A radioiodine scan is useful in staging and helps determine if the thyroid nodule is functioning or non-functioning. It is also used during postoperative surveillance to detect distant metastasis.
- A CT Scan or MRI can also provide detailed images and help in assessing the extent of the disease.
Biopsy Procedures
A definitive diagnosis of follicular thyroid cancer is made through a biopsy. The most common method is a fine-needle aspiration (FNA) biopsy. This procedure, often performed under ultrasound guidance, involves using a thin needle to extract cells from the thyroid nodule for microscopic examination.
However, it can be challenging to distinguish FTC from benign follicular adenomas based solely on the appearance of the cells under the microscope. If FNA results are inconclusive, a surgical biopsy or lobectomy may be performed to remove and examine a portion of the thyroid.
Treatment Options
The primary treatment for FTC is surgical, often followed by adjunctive therapies such as radioactive iodine therapy and thyroid hormone replacement therapy.
Surgery
The extent of surgery depends on the size and spread of the tumor. A lobectomy is a type of partial thyroidectomy that involves the removal of one lobe of the thyroid, typically for smaller tumors, while a total thyroidectomy is the surgical removal of the entire thyroid gland, often necessary for larger or more invasive tumors. Potential risks of surgical treatment include damage to the parathyroid glands or recurrent laryngeal nerve, leading to hypocalcemia or hoarseness of voice.
Radioactive Iodine Therapy
Following surgery, radioactive iodine (RAI) therapy is used to destroy any remaining thyroid tissue or microscopic cancer cells. This treatment takes advantage of the thyroid cells’ ability to absorb iodine, thereby targeting cancerous cells. Possible side effects include dry mouth, altered taste, and salivary gland swelling. Avoiding excessive iodine intake is recommended for patients undergoing RAI therapy.
Hormone Therapy
After a total thyroidectomy, patients will require lifelong thyroid hormone replacement therapy (usually levothyroxine). This is important because surgical removal of the thyroid eventually results in hypothyroidism, and so synthetic thyroid hormone (levothyroxine) helps to maintain normal thyroid hormone levels in order to maintain normal metabolism. Another benefit is that it suppresses thyroid-stimulating hormone (TSH), which can stimulate cancer growth.
Targeted Therapy
For advanced FTC, targeted therapies such as tyrosine kinase inhibitors (TKIs) may be used. These drugs specifically target specific genetic mutations or cancer cell pathways and are beneficial for patients with RAI-refractory disease.
Prognosis and Follow-Up Care
The prognosis for follicular thyroid cancer varies based on the stage at diagnosis, age, and overall health of the patient. The prognosis is generally favorable, especially when detected early and treated appropriately. The 10-year survival rate for localized FTC is around 90%. However, the prognosis worsens with advanced stages and distant metastasis.
The risk of recurrence and metastasis necessitates vigilant follow-up care, which typically involves. Regular check-ups typically include:
- Blood tests to monitor thyroglobulin levels, a marker for thyroid cancer recurrence.
- Periodic ultrasounds or other imaging studies to detect any recurrence or metastasis.
Additionally, adopting a healthy lifestyle, including a balanced diet and regular exercise, can help improve overall well-being and support recovery.
Coping Strategies and Support Systems
Getting diagnosed with follicular thyroid cancer can be overwhelming, but adopting healthy coping strategies can significantly benefit your emotional and psychological well-being. Techniques such as mindfulness and meditation, as well as counseling, can help alleviate anxiety and stress.
Building a strong support system is also essential for emotional and practical assistance. This can include family, friends, support groups, and healthcare professionals. Support groups, whether in-person or online, provide a platform for sharing experiences and gaining insights from others facing similar challenges.
Organizations like the American Cancer Society and the Thyroid Cancer Survivors’ Association (ThyCa) provide valuable resources and support networks for patients and their families.
ThyForLife Health also offers an anonymous global community supporting all thyroid conditions, including all types of thyroid cancer. Currently, the community is available only in the English language. To join this community, download the ThyForLife app on the Apple App Store or Google PlayStore.
Key takeaways
- Follicular thyroid cancer is one of the four main types of thyroid cancer and accounts for about 10-15% of all thyroid cancer cases.
- Treatment for follicular thyroid cancer often involves a combination of surgery, radioactive iodine therapy, and thyroid hormone replacement therapy.
- Early detection, appropriate treatment, and ongoing care are crucial for improving patient outcomes.
