Thyroid cancer is the most common malignant tumor of the thyroid gland, accounting for about 1% of all malignant tumors in the body. Except for medullary carcinoma, the majority of thyroid cancers originate from follicular epithelial cells. The tumor grows slowly and can be confined in the thyroid gland for several years. The lesion can spread from the primary site to other parts of the gland and lymph nodes in the neck via the intra-glandular lymphatics, and can also be confined for several years, so it is easy to ignore its nature. The incidence of thyroid cancer is increasing year by year.
Etiology
The occurrence of thyroid cancer can be influenced by hormonal, genetic and environmental factors such as radiation, goitre causing substances, iodine deficiency, etc. In addition, Hashimoto’s thyroiditis may also lead to the appearance of papillary thyroid cancer.
Pathological classification
Papillary carcinoma accounts for about 70% of all thyroid cancers in adults, while all thyroid cancers in children are often papillary carcinomas. Papillary carcinoma is commonly seen in young and middle-aged women, with women aged 21-40 being the most common. This type is well differentiated, slow growing, and has low malignancy. It has a tendency to occur multicentrically and may appear early with lymph node metastasis in the neck, so early detection and active treatment are required, and the prognosis is now better.
2.Follicular carcinoma accounts for about 15%, mostly seen in women around 50 years old. This type is fast developing, moderately malignant, and has the tendency to invade blood vessels. Cervical lymph node metastasis only accounts for 10%, so the prognosis is not as good as papillary carcinoma.
3.Undifferentiated carcinoma accounts for about 5%-10%, mostly seen in the elderly, with rapid development and high malignancy, and about 50% of them have lymph node metastasis in the neck, or invade the laryngeal nerve, trachea or esophagus, and often metastasize to distant places through blood transport. The prognosis is very poor, with an average survival of 3-6 months and a one-year survival rate of only 5%-10%.
4.Medullary carcinoma is rare. It occurs in parafollicular cells (C cells), which can secrete calcitonin. The cells are arranged in a nested or bundle shape without papillae or follicular structures, and there are amyloid deposits in their interstitium, which are undifferentiated, but their biological characteristics are different from those of undifferentiated carcinoma. It is moderately malignant and can have cervical lymph node metastasis and hematologic metastasis.
In conclusion, the biological characteristics, clinical manifestations, diagnosis, treatment and prognosis of different types of thyroid cancer are different.
Clinical manifestations
A lump found in the thyroid gland with hard and fixed texture and uneven surface is a common manifestation of all types of cancer. The gland has little up and down mobility during swallowing. Undifferentiated carcinoma may show the above symptoms within a short period of time. In addition to the obvious growth of the mass, it also has the characteristic of invading the surrounding tissues. In late stage, it may produce hoarseness, difficulty in breathing and swallowing, sympathetic nerve compression causing Horner syndrome and invasion of cervical plexus causing pain in ear, occiput and shoulder and local lymph node and distant organ metastasis. Cervical lymph node metastasis occurs earlier in undifferentiated carcinoma. In some patients, the possibility of thyroid cancer should be thought of when they seek medical attention because of metastases when the thyroid mass is not obvious. Patients with medullary carcinoma should exclude the possibility of type II multiple endocrine adenoma syndrome. Attention should be paid to the combined family history and the presence of diarrhea, facial flushing, and low blood calcium.
Diagnosis
Mainly based on clinical manifestations, thyroid cancer should be suspected if the thyroid mass is hard and fixed, the cervical lymph nodes are enlarged, or there are symptoms of pressure, or if the thyroid mass that has existed for many years increases rapidly in a short period of time.
Treatment
1.Surgical treatment
Surgical treatment of thyroid cancer includes surgery of the thyroid gland itself and cervical lymph node dissection. The scope of thyroid gland resection is still divided, with the smallest range being lobectomy plus isthmus, and the largest range being total thyroid gland resection.
2.Endocrine treatment
Thyroxine tablets should be taken for life to prevent hypothyroidism and suppress TSH in patients with secondary or total thyroid cancer.
3.Radionuclide therapy
For papillary adenocarcinoma and follicular adenocarcinoma, 131 iodine radiation therapy should be applied after surgery, which is suitable for patients over 45 years old, multiple cancer foci, locally invasive tumors and those with distant metastases.
4.Radiotherapy
Undifferentiated thyroid cancer can be treated with external radiation therapy. Since papillary thyroid cancer and follicular carcinoma are not sensitive to radiotherapy, it is not used as routine treatment.