What is follicular thyroid cancer? Symptoms, diagnosis and treatment

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Follicular thyroid cancer

Follicular thyroid cancer or thyroid follicular carcinoma is one of the two main types of thyroid cancer (the other is papillary thyroid cancer). This cancer begins in the outer layer of the cells of the thyroid gland, which are responsible for the production and secretion of thyroid hormones (especially T3 and T4). T3 hormones, although produced in very small amounts, are very important for regulating metabolism and cell function. In contrast, T4 is secreted in larger amounts and helps regulate heart rate and body temperature. Follicular carcinoma is characterized by the formation of small follicles or round structures. A cavity in the thyroid tissue. These cancer cells can invade nearby tissues and spread to distant parts of the body, especially the lymph nodes, lungs, and bones.

Features of thyroid follicular cancer

Follicular thyroid cancer has unique characteristics, the most important of which include the following:

Prevalence age: This type of thyroid cancer is mostly seen between the ages of 40 and 60.
Gender prevalence: This cancer is 3 times more common in women than in men.
Hope of treatment: The size of the tumor plays a decisive role in the hope of treatment. Tumors smaller than 1 cm usually have a good prognosis for treatment.
Relation to radiation: This type of thyroid cancer is rarely caused by exposure to radiation.
Extension to the lymph nodes: The spread of this cancer to the lymph nodes is relatively rare (about 12%).
Vascular invasion: Invasion of blood vessels (veins and arteries) inside the thyroid gland is relatively common.
Metastasis: The spread of this cancer to other parts of the body (such as the lungs or bones) is rare; But it is more likely than papillary cancer.
Cure rate: The overall cure rate for follicular thyroid cancer is high (nearly 95% for small tumors in young patients). But with increasing age, this rate decreases.

Stages of thyroid follicular cancer

Staging is the process of determining whether and how far the cancer has spread. Follicular thyroid cancer staging is a vital factor in choosing treatment methods, determining the amount of surgery and predicting the probability of recovery. Follicular thyroid cancer staging system is different from other cancers and in it, the patient's age is also considered. In the American Joint Committee on Cancer (AJCC) staging system for follicular and papillary thyroid cancers, the current age cutoff point is 55 years. This means that cancer staging for patients under 55 years old is different from patients over 55 years old.

TNM staging system is usually used to determine the stage of follicular thyroid cancer. The letters T, N, and M indicate the size of the tumor, spread to the lymph nodes, and the presence of metastasis, respectively. Doctors determine the stage of cancer by collecting and combining information about T, No, and M. In other words, the TNM letters are a tool to more accurately assess how far the cancer has spread, and the numbers 1 to 4 are a summary of this information used to determine the overall stage of the cancer. With this in mind, the TNM system classifies patients aged 54 years or younger as stage 1 thyroid cancer if the cancer is limited to the thyroid and its nearby areas. If the cancer has spread to distant parts of the body, it is labeled as stage 2.

Follicular cancer staging

The staging of follicular thyroid cancer in patients 55 years and older is as follows:

Stage 1: The cancer is limited to the thyroid or the tumor is less than 2 cm in diameter.
Stage 2: The cancer has spread to nearby lymph nodes but has not yet spread to distant sites, or the tumor is larger than 4 cm in diameter and has spread to the striated muscles around the thyroid.
Stage 3: The cancer has spread beyond the thyroid to nearby structures in the neck such as the larynx or esophagus.
Stage 4a: Cancer has spread extensively beyond the thyroid and into the spine or major blood vessels.
Stage 4b: Cancer has spread to distant organs, bones, or other vital structures.

Symptoms of thyroid follicular cancer

Follicular thyroid cancer (like other thyroid cancers) usually has no symptoms in the early stages. However, as the cancer progresses, you may experience symptoms such as the following:

A painless lump in the front of the neck or a thyroid nodule (which may be felt as a small, palpable bump in the neck)
enlargement of the thyroid gland (which is also called goiter)
breathing problems (such as shortness of breath or a feeling of suffocation)
Hoarseness or changes in voice
Neck pain
Swollen lymph nodes (which may be felt as small, tender bumps in the neck or under the jaw)

Note that these symptoms do not necessarily indicate cancer and may be caused by non-cancerous diseases such as thyroid inflammation.

Diagnosis of thyroid follicular cancer

To diagnose thyroid cancer, the doctor will first review your medical history, ask about your family history of thyroid cancer, and then perform a physical examination of the thyroid gland. During the exam, he will check for goiters (significant enlargement of the thyroid gland) or any lumps. If your doctor suspects follicular thyroid cancer, he may recommend additional tests, which may include:

Ultrasound:

The simplest method is to check the condition of the thyroid gland; But it cannot be considered as a definitive method for diagnosing thyroid follicular cancer.

Digital imaging:

The doctor may recommend an MRI or CT scan to obtain detailed images of the thyroid gland.

Fine needle aspiration biopsy:

In thyroid biopsy, a thin needle is inserted into the neck lump to collect a sample of cells to identify cancer cells under a microscope.

Core needle biopsy:

If the results of a fine-needle aspiration biopsy are inconclusive, your doctor may choose to perform a core needle biopsy, which involves using a larger needle.

After follicular thyroid cancer is diagnosed, more tests are done to determine the stage of the cancer and plan the appropriate treatment. These tests usually include blood tests, more detailed imaging procedures, and sometimes surgery to remove the thyroid gland (both to diagnose and treat follicular thyroid cancer).

Follicular thyroid cancer treatment methods

Treatment of follicular thyroid cancer is determined based on the cancer stage, the patient's general health status and his treatment preferences. The main goal is to completely remove cancer cells and prevent the disease from returning. Methods of thyroid cancer treatment are usually a combination of surgery, radioactive iodine, and thyroid hormone replacement therapy, which we discuss below.

Thyroidectomy (removal of the thyroid gland):

It means removing part of the thyroid gland (partial thyroidectomy) or the entire thyroid gland (total thyroidectomy). If the cancer has spread to the lymph nodes, the lymph nodes may also be removed.

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Radioactive iodine (iodine therapy):

After surgery to destroy the remaining thyroid tissue, radioactive iodine is injected into the thyroid tissue.

Hormone replacement therapy:

After partial or complete removal of the thyroid gland, thyroid hormone tablets are prescribed to provide the body with essential hormones and prevent cancer cells from growing again.

Chemotherapy and radiation therapy:

In more advanced cases of follicular thyroid cancer, non-surgical methods such as chemotherapy or radiation therapy are used to target and fight cancer cells.

Targeted therapy:

In this method, drugs are used that specifically bind to molecules or genes in cancer cells and destroy them. Targeted therapy is an advanced treatment option that can be effective in certain cases, especially in advanced stages of follicular thyroid cancer.

Immunotherapy (therapeutic immunity):

Immunotherapy drugs are administered by intravenous injection. They are usually used as second-line treatments when initial targeted therapies are not effective.

Essential follow-ups after follicular carcinoma treatment

All patients with follicular thyroid cancer should be followed for life to monitor their disease and hormones. Patients should have their blood thyroglobulin levels checked annually and also have a high-resolution ultrasound of the neck. Serum thyroglobulin level is generally not useful for early diagnosis of thyroid cancer; But it is very useful in the follow-up of differentiated carcinomas (in case of complete thyroidectomy). The high level of serum thyroglobulin, which is low at first after total thyroidectomy and then gradually increases especially with TSH stimulation, almost indicates the recurrence of cancer. Values greater than 10 ng/mL are often associated with structural (detectable) recurrence; Even if the iodine scan is negative. To more accurately check the possibility of cancer returning in the original tumor site, nearby lymph nodes or other parts of the body, it is necessary to use diagnostic imaging methods to follow high levels of thyroglobulin.

Follicular thyroid cancer survival rate
Follicular cancer survival rates are estimates based on the percentage of patients with a similar stage of cancer who survive for 5 years or more after their cancer is diagnosed. These rates are based on the results of a large number of people in the past. These rates may give patients and physicians an understanding of the likely success rate of treatment; But they cannot predict how a particular patient will recover.

The American Cancer Society reports that the relative five-year survival rates for follicular thyroid cancer are as follows:

More than 99.5% for patients whose cancer has not spread outside the thyroid.
98% if the cancer has spread to nearby areas.
67% if the cancer has metastasized to distant parts of the body.

What is the prevalence of thyroid follicular carcinoma?

About 10 to 15% of all thyroid cancers are follicular thyroid cancer. In fact, this cancer is the second most common thyroid cancer. Most people with thyroid cancer have papillary thyroid cancer (between 70 and 80% of all thyroid cancers).

How curable is thyroid follicular carcinoma?

Follicular thyroid cancer is usually very treatable; Especially when diagnosed early. The success of the treatment depends on various factors, including the stage of the cancer at the time of diagnosis, the extent of its spread, the age of the patient, the general state of health, and the characteristics of the cancer cells. Compared to more aggressive thyroid cancers such as anaplastic thyroid cancer, follicular thyroid cancer often progresses more slowly. As a result, early diagnosis significantly increases the chances of successful treatment.

Last word

Follicular thyroid cancer, although less common than papillary thyroid cancer, is more aggressive and occurs at an older age. Diagnosis of follicular thyroid cancer includes medical history review, physical examination, imaging tests, and biopsy. Cancer staging using the TNM system helps to determine the spread of cancer and choose the appropriate treatment method. Follicular thyroid cancer is usually curable; Especially when it is diagnosed early.

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