Thyroid abnormalities are sometimes due to X-ray treatment, received in childhood, to the head and neck area. This method of treatment for children was frequently used prior to 1950 for a number of conditions. It is advisable to consult your physician if you or members of your family have ever received this treatment.
The following information from the Canadian Cancer Society is important for you to understand.

Causes of Thyroid Cancer
The only known risk for thyroid cancer is radiation. From the 1920s to the mid-1950s, thousands of children received X-ray treatments to the head and neck areas. Back then, X-ray therapy was used to treat swollen tonsils and adenoids, ring worm of the scalp, acne and other non-cancerous conditions; no one foresaw its long-term complications.
As follow-up studies began to link radiation therapy to higher rates of thyroid cancer, this type of therapy was abandoned. Although very few people who underwent X-ray therapy as children are actually diagnosed today with thyroid cancer, anyone who had X-rays to the head and neck areas should regularly consult a physician.

Hope for the Future
Detection of thyroid cancer in people who had X-ray treatments as children is the greatest hope for the future. Even though most of these people will never develop cancer of the thyroid, a physician should regularly check them whether or not they have symptoms. Further hope for the future lies in uncovering other potential causes of this type of cancer.

(Excerpts from Facts on Thyroid Cancer, Canadian Cancer Society, 1986)