Radiotherapy in childhood
The thyroid gland is particularly sensitive to radiation. The intrinsic reason why the thyroid is more susceptible to radiation damage in children compared to adults is not clear.
Children who have had other cancers in childhood and have received radiation therapy may also develop thyroid disease (hypothyroidism, nodules, or even cancer) in late adolescence, with a risk about 40 times higher than normal. Overall, the incidence of thyroid cancer is more than 10% of all cancer survivors after radiation therapy. Most thyroid disease appears about 15 years after initial treatment, but it has been reported up to 30 years later. Some young children develop the disease after 5 years.
Until 1980, radiation therapy was used for children with a variety of conditions, including tinea capitis, facial acne, and enlarged thymus. This practice has long been abandoned, and it has been learned that the younger the child is treated with radiation, the greater the chance of thyroid cancer and the earlier the disease develops.
In addition, small doses of radiation appear to be more likely to cause thyroid abnormalities (such as cancer) than larger doses of radiation therapy. This type of damage (DNA mutations) increases the risk of uncontrolled cell growth, leading to the development of thyroid nodules or thyroid cancer.
The thyroid may also be irradiated when children with other types of tumors (such as brain tumors, leukemia, and lymphoma) receive radiation therapy. Radiation doses as low as 50 rad (rad is a unit of radiation absorbed dose, the English symbol for rad, and 100 rad = 1 gray) may cause enough damage to the thyroid to increase the risk of thyroid nodules and thyroid cancer. children under 10 years of age who receive radiation doses of 200 to 2000 rad to the head and neck are at greatest risk.
Radiological Exposure from the Environment
Exposure to radiation is associated with a general increase in thyroid cancer in children. An extreme example is the Chernobyl nuclear power plant accident that occurred in Belarus in April 1986. The increased incidence of thyroid cancer in children began to appear 5 years after the accident. Because thyroid cancer usually develops slowly, the effects of this accident are continuing to show up, even 20 years after the accident.
Heredity
Some types of papillary thyroid cancer are heritable. That is, one parent is at risk for the disease and the other parent is not, passing the risk of the disease on to offspring.
Possible genetic factors should be considered if thyroid cancer runs in the family for several generations or if Gardner syndrome (familial colon polyposis), Cowden syndrome (also known as multiple malignancy syndrome), and Carney syndrome are present.
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This article is from http://www.thyca.org网站, compiled by Tencent Medical Dictionary medical team, and used with permission.