What are the causes of thyroid cancer? Not all is known about this question. However, we do know that thyroid cancer is found more often when the neck was irradiated with X-rays. This cancer causing effect lasts for about 30 to 40 years. This is how long the incubation time can be. In the past irradiation was popular for treating children with an enlarged thyroid, which we now know is just a normal, transitory growth spurt phenomenon.
Other illnesses such as severe acne were at one time also treated with irradiation. Women seem to have more thyroid disease including cancer. They are also more prone to Hashimoto’s disease and the pregnancy associated silent lymphocytic thyroiditis. It is more common in a young age group, but tends to be less invasive (papillary cancer). Iodine deficiency leads to a higher rate of goiters and this likely is due to an increase of the hormone TSH (thyroid stimulating hormone) from the pituitary gland. In these nodules there is a higher incidence of thyroid cancer. In this latter scenario it is usually the papillary thyroid cancer.
TSH has a thyroid tumorigenic effect
It appears then that TSH has a thyroid tumorigenic effect at high levels. However, small amounts of thyroid and thyroid replacement hormones will normalize the TSH level. Obviously this is a complex area of medicine and the physician with the help of an endocrinologist will help the patient so that the hormone balance is brought to as close to normal as possible. A minority of thyroid cancers are of a genetic origin (Men IIa, Men IIb, Medullary thyroid carcinoma). We also know that oncogenes play a role in the development of thyroid cancer. Two of them are well known in researcher circles, the RAS and PTC oncogenes. Mutations of these thyroid controlling genes play an important role in the transformation from a normal to a cancerous thyroid cell.
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