Thyroid cancer accounts for 1.3% of systemic malignant tumors and 4.8%-16.5% of thyroid tumors, and is the most common endocrine system tumor. Generally, the incidence of thyroid cancer is higher in females, while the proportion of thyroid cancer in male thyroid nodules is much higher than that in females; unlike the general feature that cancer tumors tend to occur in the elderly, thyroid cancer tends to occur in young adults. It has been reported that thyroid cancer accounts for 15.6%-28.7% of single nodules in the thyroid gland, while the percentage of multiple nodules is about 10%.
Thyroid cancer is generally divided into four pathological types: papillary carcinoma, follicular carcinoma, medullary carcinoma and undifferentiated carcinoma. Different pathological types have different clinical manifestations.
1.Papillary carcinoma.
It is a kind of well-differentiated thyroid cancer, which occurs in young women and accounts for about 60% of all thyroid cancers; the cancer grows slowly and can take as long as 10-30 years from the onset to the consultation. The lesion is usually solitary and varies in size. Large tumors are often accompanied by cystic changes and are easily misdiagnosed as thyroid cysts. Although papillary carcinoma may have lymph node metastasis in the neck at an early stage, it is less malignant and has a 10-year survival rate of 88%.
2.Follicular carcinoma.
Follicular carcinoma is a solid tumor with envelope and reddish-brown color on the cut surface, often with fibrosis, calcification and hemorrhagic necrosis. Follicular carcinoma is mostly seen in middle-aged people aged 40-60 years old, and its clinical manifestation is similar to papillary carcinoma, but the cancer mass is usually larger and less local lymph node metastasis, but more metastasis to lung and bone through blood.
3.Medullary carcinoma of thyroid.
Medullary thyroid carcinoma is a kind of moderately malignant carcinoma that can occur at any age and about 10% is familial. It can occur at any age and about 10% are familial. In addition to the thyroid mass and cervical lymph node metastasis like other thyroid cancers, about one-third of patients have a history of chronic diarrhea with facial flushing and other symptoms.
4.Undifferentiated thyroid cancer.
It is less common, accounting for about 15% of all thyroid cancers, and is more common in the elderly. Undifferentiated carcinoma grows rapidly and often invades surrounding tissues at an early stage. The carcinoma has no envelope and is flesh-colored with bleeding and necrosis. The main manifestation is a mass in the anterior neck area, which is hard, fixed and with unclear boundary. It is often accompanied by dysphagia, dyspnea, hoarseness and pain in the neck area. This tumor is highly malignant and the average survival time is about 3-6 months.
Most of them are asymptomatic. Occasionally, a nodule or lump is found in the anterior neck area, and some lumps have existed for many years but have only recently grown rapidly or metastasized. Some lumps have been present for many years and have only recently grown rapidly or metastasized. Thyroid cancer lumps are likely to produce early pressure symptoms, such as hoarseness, dyspnea, difficulty in swallowing, or signs such as irritated veins on the affected side and facial edema. Thyroid cancer can also develop lymph node metastasis and distant metastasis, such as lung metastasis and bone metastasis. Therefore, the thyroid gland should be carefully examined when there are hard and fixed lymph nodes in the neck or metastases in the lung and bone with unknown primary foci. It is important to note that the benignity or malignancy of a nodule is not related to the size of the nodule; it is not related to whether the nodule is palpable or not; and the risk of malignancy in a multinodular goiter is the same as that of a single nodule. Even if a thyroid nodule is diagnosed as benign, the patient needs to be followed up. Benign nodules usually get smaller, while malignant nodules increase in size, albeit slowly.
Surgical treatment.
Complete surgical excision is the most basic treatment for follicular and papillary thyroid carcinoma. Except for tumors less than 1 cm in diameter and confined to the thyroid gland, total or near-total thyroidectomy should be performed, and subtotal thyroidectomy and single lobectomy are not recommended.
Radioactive iodine 131 treatment.
Radioactive iodine 131 treatment not only can completely destroy the residual thyroid tissue after surgery, but also facilitates the determination of tumor marker – thyroglobulin (Tg) content in blood, which can easily and sensitively monitor whether the tumor has recurrence and metastasis. In addition, local soft tissue and lymph node metastases that remain after surgery or cannot be surgically removed, and distant metastases such as lung and bone should be treated with iodine-131. Patients need to stop taking thyroxine (eugenol) for about 3-4 weeks before treatment. The purpose is to increase the body’s thyrotropin (TSH) significantly, thus enhancing the ability of metastases from thyroid cancer to take up iodine-131. Medullary thyroid carcinoma and undifferentiated carcinoma generally do not have the ability to uptake iodine-131, therefore, iodine-131 therapy is not suitable.
Thyroid hormone therapy.
Thyroid hormone therapy suppresses human serum thyrotropin, which promotes the growth of thyroid cancer cells. Therefore, thyroid hormone therapy can remove the environment that promotes the growth of thyroid cancer cells and achieve the purpose of treatment.
The significance of thyroid hormone therapy.
(1) Maintaining the normal function of the thyroid gland;
(2) Inhibit the secretion of thyroid stimulating hormone from the pituitary gland. Therefore, thyroid hormone replacement therapy is used for both total and partial thyroidectomy.
The goal of long-term follow-up for patients with differentiated thyroid cancer is to closely monitor patients with possible recurrence, and early detection of recurrent foci can help to implement effective treatment for patients.
Ultrasound examination of the neck is highly sensitive to detect metastases in the neck. Ultrasound examination of the neck should be performed at 6 and 12 months after treatment to assess the condition of the thyroid gland and bilateral cervical lymph nodes.
For one year after surgery or iodine 131 radiation therapy, blood should be drawn every three months to check free thyroxine, thyroglobulin and thyroid stimulating hormone (TSH) concentrations. After one year, they should be checked every six months. If everything is normal, after two years, the test can be changed to once a year.
Thyroglobulin concentration can be used as an indicator of recurrence of papillary and follicular carcinoma. If the serum thyroglobulin concentration exceeds 10ng/ml, further tests and treatment are required.
Diagnostic whole-body iodine scan is also the most useful follow-up method when there is no or only a small amount of normal thyroid tissue remaining after treatment. In addition, all cancer patients should have an annual chest x-ray to check for lung metastases. Patients with medullary carcinoma can have their thyrocalcitonin levels tracked to detect recurrence of cancer cells.
Compared with other malignant tumors, thyroid cancer is relatively slow to develop and is generally not life-threatening. Therefore, there is no need to worry too much about thyroid cancer, as long as you maintain a positive and healthy attitude and choose the right treatment, you can live and work like a healthy person. Generally speaking, the prognosis of thyroid cancer is good, for example, the twenty-year survival rate of papillary carcinoma can exceed 90; the ten-year survival rate of follicular carcinoma is about 80; the ten-year survival rate of medullary carcinoma is about 60 to 70; among them, only undifferentiated carcinoma has a higher mortality rate, and patients often die within a few months after the diagnosis is confirmed.
The incidence of Hashimoto’s thyroiditis combined with thyroid cancer, especially papillary thyroid carcinoma, has been on the rise in recent years. Hashimoto’s thyroiditis may be a high risk factor for the development of thyroid cancer. There is no treatment for autoimmune thyroiditis that addresses the cause of the disease. Restriction of iodine intake may help to slow the progression of autoimmune destruction of the thyroid gland. Patients with pre-existing hypothyroidism or significant subclinical hypothyroidism must be treated with thyroid hormone replacement. Selenium is an essential trace element in the body and is an antioxidant.
It has important physiological functions such as anti-aging, anti-tumor, cardiovascular protection, and antagonism to heavy metal toxicity. Selenium can improve the immune function of the body. Selenium intervention therapy can reduce or inhibit the immune damage of autoimmune thyroiditis. 2003 U.S. Food and Drug Administration (FDA) confirmed that selenium is a cancer suppressant, selenium supplementation reduces the mortality rate of tumors by half, high-dose selenium supplementation can reduce the toxicity of chemotherapy drug treatment, and can significantly improve the effect of radiotherapy and chemotherapy treatment.