There are four common types of thyroid cancer: papillary (including mixed papillary follicular carcinoma), follicular, medullary (solid with amyloid thyroid tumor), and undifferentiated carcinoma. Interstitial cell carcinoma of the thyroid is very rare.
Thyroid cancer is generally not highly malignant, and if treated properly, papillary and follicular thyroid cancer can reach normal life expectancy. Yang Hui, Department of Nuclear Medicine, Henan Cancer Hospital
Papillary carcinoma accounts for 60%-70% of all thyroid cancers. It is less malignant and has a 10-year survival rate of 88%, mostly seen in children or young (before 40 years old) female patients, with 2-3 times more female patients than male. Younger patients are more common, but older patients are slightly more malignant. Most often seen in patients with a history of radiation exposure, the tumor grows slowly and can be confined within the thyroid gland for several years, spreading via the lymphatic system. TSH-dependent tumors can develop on the basis of goiter secondary to Hashimoto’s thyroiditis. The lesions are usually solitary and vary in size, with the smallest being less than 0.5 cm in diameter, called microcarcinoma; those less than 1 cm in diameter are called occult carcinoma, while large lesions can be larger than 10 cm in diameter.
Follicular carcinoma accounts for about 10%-15% of thyroid cancer. It is less malignant, with a 10-year survival rate of 50-90%, and is mostly seen in women aged 40-60. It has a long course, slow growth and few symptoms except for a painless lump in the thyroid area, sometimes it is clinically difficult to distinguish from benign adenoma, often metastasizing to lung and bone, less to cervical lymph nodes, and TSH dependent. A few follicular carcinomas infiltrate and destroy adjacent tissues and can present with symptoms such as airway obstruction.
Medullary carcinoma accounts for 3% to 10% of all thyroid cancers, with moderate malignancy and 10-year survival rate of 70-75%. It can occur at any age and there is no significant difference in the incidence rate between men and women, most of them are sporadic and about 10% are familial. It often metastasizes along lymphatic and blood channels, and about 30% of patients have a history of chronic diarrhea.
Undifferentiated carcinoma is less common, including large cell carcinoma, small cell carcinoma, squamous cell carcinoma, sarcoma, carcinosarcoma, fibrosarcoma, malignant fibrous histiocytoma, and poorly differentiated papillary carcinoma and follicular carcinoma in the thyroid gland, etc. It occurs in the elderly and has a high degree of malignancy. Due to the short course and rapid progression of the disease, most patients have lost the chance of radical treatment at the first diagnosis, and the prognosis is poor. The main manifestation is a mass in the anterior neck area that is hard, fixed and poorly defined. It is often associated with dysphagia, dyspnea, hoarseness and pain in the neck area. Both necks are often accompanied by enlarged lymph nodes, and hematologic metastases are also more common.