Thyroid Cancers and Thyroid Nodules in an area of Nuclear Fallout from the Nevada Nuclear Test Site

Thyroid nodules are very common: being found in 4%–8% of adults by examination, and 10%–41% by ultrasound, and in 50% of autopsies. The prevalence of thyroid nodules increases with age. The likelihood that a nodule is malignant is affected by a variety of risk factors. Malignancy is more common in nodules found in patients who are younger than 20 or older than 60 years of age than in patients between 20 and 60 years of age. Physical examination factors associated with increased likelihood of malignancy include firmness of the nodule, rapid growth, fixation to adjacent structures, vocal cord paralysis, and enlarged regional lymph nodes. In addition, a history of neck irradiation or a family history of thyroid cancer increases the risk that a thyroid nodule is malignant.

Compared with the very high prevalence of thyroid nodules, thyroid cancer is not common. The overall incidence of cancer in patients with thyroid nodules is approximately 5%-13%.  In patients with multiple nodules, the cancer rate per nodule decreases, but the decrease is proportional to the number of nodules so that the overall rate of cancer per patient is about 10%–13%. Many patients present for ultrasound evaluation of a suspected thyroid nodule found incidentally with other imaging tests, such as carotid ultrasound or cervical MRI.

The upper Rocky Mountain states lie in the direct path of nuclear fallout from the atmospheric testing that occurred in Nevada from 1951 to 1964.  In a recent survey done by the NCI examining the exposure received as a direct result of this nuclear testing by location, it was noted that the upper Rocky Mountains received on average between 1.5 and 15.8 rads to their thyroid. The University of Utah, under contract with the NCI, is carrying out a study to determine if the incidence of thyroid disease among identified populations in Utah may be related to exposure from fallout originating at the Nevada Test Site.  Based on the rates of thyroid neoplasms, it has been concluded that living near the NTS in the 1950s has not resulted in a statistically significant increase of thyroid neoplasms in subjects from UT/NV when compared with subjects of the same age and gender living in AZ. 

At the Huntsman Cancer Institute, we are very experienced with the assessment and ultimate treatment of thyroid nodules and thyroid cancer.  The Head and Neck Oncology team sees the majority of thyroid nodules being considered potentially cancer at the University of Utah and the upper rocky mountain states.  This experience helps us to provide the most appropriate care for the thyroid problem that you are struggling with.