What Are the Causes of Thyroid Cancer?

Thyroid cancer is the most common malignant tumor of the thyroid gland, accounting for about 1% of systemic malignancies. It includes four pathological types: papillary carcinoma, follicular carcinoma, undifferentiated carcinoma, and medullary carcinoma. Papillary carcinoma with the lower malignancy and better prognosis is the most common. Except for medullary carcinoma, most thyroid cancers originate from follicular epithelial cells. Incidence is related to region, race, and gender. It is more common in women, and the incidence rate for men and women is 1% (2 to 4). It can occur at any age, but it is more common in young adults. Most thyroid cancers occur in one lobe of the thyroid gland, often as a single tumor.

Basic Information

nickname

Malignant goiter

English name

thyroid carcinoma

Visiting department

Surgery, Oncology

Common causes

unknown

Common symptoms

Mass found in thyroid, hard and fixed, uneven surface

Causes of thyroid cancer

1. Iodine and thyroid cancer

Iodine is an essential trace element in the human body. Iodine deficiency leads to a decrease in thyroid hormone synthesis, an increase in thyroid stimulating hormone (TSH) levels, stimulation of thyroid follicular hyperplasia and hypertrophy, the occurrence of goiter, the appearance of thyroid hormones, and an increase in the incidence of thyroid cancer. Not yet consistent. And high iodine diet may increase the incidence of papillary thyroid cancer.

2. Radiation and thyroid cancer

Irradiating the thyroid of experimental mice with X-rays can promote animal thyroid cancer, deformed cell nuclei, and greatly reduce the synthesis of thyroxine, leading to canceration; on the other hand, it destroys the thyroid gland and cannot produce endocrine, and the large amount of TSH secretion caused by it Can promote canceration of thyroid cells.

3. Chronic stimulation of thyroid stimulating hormone (TSH) and thyroid cancer

Increased serum TSH levels induce nodular goiter. Follicular thyroid carcinoma can be induced by mutagens and TSH stimulation, and clinical studies have shown that TSH inhibition plays a role in the treatment of differentiated thyroid cancer after surgery. Important role, but whether TSH stimulation is the cause of thyroid cancer remains to be confirmed.

4. The role of sex hormones and thyroid cancer

Because there are significantly more women than men in well-differentiated thyroid cancer patients, the relationship between sex hormones and thyroid cancer is valued. Some people have studied the sex hormone receptors in thyroid cancer tissues and found that the sex hormone receptor: estrogen receptor ( ER) and progesterone receptor (PR), and ER in thyroid cancer tissues, but the effect of sex hormones on thyroid cancer is still inconclusive.

5. Goiter substances and thyroid cancer

Any substance that can interfere with the normal synthesis of thyroid hormones and produce thyroid gland will become a goiter substance, including cassava, radish, cabbage, thiouracil, thiocyanate, sodium para-aminosalicylic acid, buta pine, potassium perchlorate , Cobalt, lithium salts and other foods and medicines, as well as drinking water containing sulfur hydrocarbons, calcium and fluorine.

6. Other thyroid diseases and thyroid cancer

In some patients with benign thyroid diseases such as nodular goiter, hyperthyroidism, and hyperthyroidism, there are a small number of patients with thyroid cancer. Thyroid adenoma may also become cancerous.

7. Family factors and thyroid cancer

About 5% to 10% of patients with medullary thyroid cancer have a significant family history and are autosomal dominant. It is also clinically seen that more than two members of a family are suffering from papillary cancer.

Clinical manifestations of thyroid cancer

There are usually no obvious symptoms and signs in the early stage. Usually, a small thyroid mass is found by thyroid palpation and neck ultrasound during physical examination.

A typical clinical manifestation is that a mass is found in the thyroid gland, and the texture is hard and fixed, and the surface is uneven, which is the common manifestation of various types of cancer. Glands are less mobile when swallowing. Undifferentiated cancer can appear the above symptoms in a short period of time. In addition to the obvious increase in mass, it also has the characteristics of invading surrounding tissues.

Late stage can produce hoarseness, breathing, dysphagia and sympathetic nerve compression caused Horner syndrome and cervical plexus violations appear ears, pillows, shoulders and other pain and local lymph nodes and distant organ metastases. Cervical lymph node metastasis occurs earlier in undifferentiated cancer.

Due to the tumor itself, medullary carcinoma can produce calcitonin and serotonin, which causes diarrhea, palpitations, flushing and other symptoms.

Thyroid cancer test

1.B ultrasound

Neck ultrasound is the first test for diagnosing the nature of a goiter, and can find smaller masses that are difficult to find on palpation.

2. Nuclide scanning

Solid thyroid nodules should be routinely scanned with nuclide scans, and thyroid cancer I and Tc imaging are mostly cold nodules.

3.CT and magnetic resonance imaging

It is mainly used to understand the scope and metastasis of thyroid cancer.

4. Thyroid biopsy

Needle aspiration cytology or puncture histology under ultrasound guidance to determine the benign and malignant masses.

5. Blood test

Before and after treatment of thyroid tumors, thyroid stimulating hormone, thyroid hormone, thyroglobulin, calcitonin, and thyroxine binding capacity are often checked. Detection of serum calcitonin levels can help the diagnosis of medullary carcinoma.

Thyroid cancer diagnosis

All thyroid masses, regardless of age, single or multiple, including texture, should be vigilant. Mainly based on clinical manifestations, thyroid cancer should be suspected if the goiter is hard, fixed, and cervical lymph nodes are swollen, or there are compression symptoms, or those who have had thyroid masses for many years, which increase rapidly in the short term. Combined with B-ultrasound, nuclide scanning, needle aspiration cytology, etc. to determine the nature of the mass. In some patients, the thyroid mass is not obvious. When seeking medical treatment because of metastatic lesions, the possibility of thyroid cancer should be considered. Patients with medullary carcinoma should rule out the possibility of type multiple endocrine adenoma syndrome. Attention should be paid to combined family history and diarrhea, facial flushing, and hypocalcemia.

Thyroid cancer treatment

The principle of treatment for thyroid cancer is a comprehensive treatment based on surgery. The treatment method mainly depends on the age of the patient, the pathological type of the tumor, the degree of the lesion, and the general condition. Surgery is the first choice, followed by endocrine therapy, if necessary, comprehensive treatment including radiotherapy and chemotherapy.

Surgical treatment

Surgical treatment of thyroid cancer is its main treatment method, including surgery of the thyroid itself, and cervical lymph node dissection. Regardless of the type of pathology, as long as there is surgical indication, it should be surgically removed as far as possible. For well-differentiated papillary carcinoma or follicular carcinoma, even patients with local recurrence after surgery can be treated again. The range of thyroid resection is related to the pathological type and stage of the tumor. The smallest range is glandular lobe and isthmus resection, and the largest range is total thyroid resection.

2. Endocrine therapy

Patients with subtotal or total resection of thyroid cancer should take thyroxine tablets for life to prevent hypothyroidism and inhibit TSH. Both papillary adenocarcinoma and follicular adenocarcinoma have TSH receptors, and TSH can affect the growth of thyroid cancer through its receptors. In China, dry thyroid tablets or levothyroxine are generally used. Plasma T ₄ and TSH levels should be measured regularly to adjust the dosage so that the body's thyroid hormone is maintained at a level slightly higher than normal but lower than hyperthyroidism.

3. Radionuclide therapy

For papillary adenocarcinoma and follicular adenocarcinoma, postoperative application of I radiation therapy is suitable for patients over 45 years of age, multiple cancerous lesions, locally invasive tumors, and those with distant metastases. Precautions for I treatment: Patients should stay in an isolation ward for the first 3 to 5 days after taking I, and try to avoid contact with pregnant women and children after being discharged from the hospital; Review after 3 to 6 months of I treatment; Pregnancy can be considered within one year after the treatment is completed; Thyroxine preparations should be stopped and iodine-containing diets should be restricted during treatment.

4. External Radiation Therapy

Except for undifferentiated thyroid cancer, other types of thyroid cancer are less sensitive to radiotherapy, so external radiation therapy is the main treatment for undifferentiated cancer. Differential cancer does not require conventional radiotherapy. If there is residual or isolated distant metastases after surgery, postoperative radiotherapy should be given in time to reduce the local recurrence rate as much as possible.

5. Other treatments

Generally used for adjuvant treatment or advanced palliative treatment of undifferentiated cancer. For advanced patients who cannot be operated or tumors involve important blood vessels and organs, interventional treatment can be tried to extend the survival time of patients. For patients who cannot tolerate surgery, physical ablation methods such as microwave, laser, and radio frequency can also be considered.

Prognosis of thyroid cancer

Mainly related to pathological type, age, tumor size and so on. Papillary and follicular carcinomas have a good prognosis, while undifferentiated carcinomas have the worst prognosis. Age is a key factor affecting the prognosis of papillary and follicular carcinomas. The recurrence rate and mortality rate increase with age.