How high is the incidence?
Thyroid cancer can occur at any age. In the United States, thyroid cancer is rare in children under 10 years of age, with an annual incidence of 1 in a million; in adolescents 15 to 19 years of age, the annual incidence is about 15 in a million.
In children under 10 years of age, the risk is similar for boys and girls, and in children older than 10 years of age, the disease is more common in girls. in adolescents aged 15 to 20 years, the incidence is more than 5 times higher in girls than in boys. The number of female adolescents with thyroid cancer in the United States has increased slightly in recent years; there has been no increase in male adolescents or children under 15 years of age.
What types are there?
There are two main types.
There are two main types:
- Differentiated thyroid cancer (DTC): This includes papillary thyroid cancer (PTC), follicular thyroid cancer (FTC), and their variants. Papillary thyroid cancer is the most common, accounting for about 90% of thyroid cancers in children. Follicular thyroid cancer is not as common. Differentiated thyroid cancer accounts for only 1% of cancers in children aged 5 to 9 years and about 7% of cancers in patients aged 15 to 19 years.
- Medullary thyroid cancer (MTC): accounts for 5% to 10% of all thyroid cancers and is very rare in children and adolescents, occurring in less than one in a million each year in the United States.
What are the characteristics?
Papillary carcinoma
Papillary carcinoma is the most common and has the best outcome compared to other types of thyroid cancer. Treatment is similar to that for adults.
Papillary carcinoma in children and adolescents is usually more severe at diagnosis than in adults. The vast majority of children are diagnosed with metastases to the lymph nodes in the neck. About 10% to 20% of children have distant metastases, most commonly to the lungs. In adults, the incidence of distant metastases is only 5%. Children are more likely to have recurrence than adults.
Despite this, the long-term prognosis for children with papillary thyroid cancer is very good if treated appropriately.
Follicular carcinoma
The primary lesion is often a single lesion within the thyroid gland. Lymph node metastases may occur in less differentiated follicular carcinomas, but are uncommon.
Follicular carcinoma is uncommon in children. It has a worse outcome compared with papillary carcinoma because it invades blood vessels and increases the risk of distant metastases, such as lung and bone. Nevertheless, pediatric patients have a better outcome compared to adult patients with similar disease. Few children die from follicular carcinoma, and even when distant metastases occur, they survive for years to decades.
The goal of treatment for follicular carcinoma is to destroy the lesion and minimize the likelihood of recurrence. When a cure is not possible, doctors focus on stabilization and symptomatic treatment.
What factors increase the risk of thyroid cancer in children and adolescents?
The National Cancer Institute (NCI) believes that the cause of thyroid cancer is still unknown. Research suggests that certain factors may increase the chance of developing thyroid cancer. In general, prepubescent children are at higher risk for thyroid cancer and have family or genetic factors (history of thyroid disease or related conditions) and a greater risk of developing cancer.
The following factors may increase the risk of thyroid cancer in children and adolescents:
Differentiated thyroid cancer
Exposure to ionizing radiation at a young age is a risk factor. In the treatment of childhood cancers, either ingestion of radioiodine or external exposure increases the risk of disease. A classic example: the increased incidence of thyroid cancer in children after the Chernobyl nuclear power plant accident in 1986.
In general, differentiated thyroid cancer is not directly inherited, but it still exhibits some genetic predisposition, and the mechanism is unclear.
Papillary thyroid carcinoma may occur in patients with some hereditary syndromes such as Gardner syndrome, Carney complex (CNC). A subset of follicular carcinomas may be associated with mutations in the PTEN gene, which can cause Cowden disease.
In tumor cells, some genetic mutations (RET/PTC, BRAF, etc.) have also been found to be associated with the development of differentiated thyroid cancer. However, experts believe that these mutations are not inherited.
Medullary thyroid cancer
The development of medullary thyroid cancer in children and adolescents is almost always familial. This means that it is caused by specific mutations in somatic DNA, mutations that usually occur in the RET proto-oncogene.
This article is from http://www.thyca.org网站, compiled by the Tencent Medical Dictionary medical team and used with permission.