Hyperthyroid Follow-Up Study

Overview

Background: Hyperthyroidism is a common disease. It is very common for women. It is usually treated with Radioiodine (I-131). Some people think that this might cause cancer, even many years later. Past studies of people with hyperthyroidism have not been clear about cancer risks after I-131. Researchers want to look at a group of people with the disease who got I-131 many years ago. They want to look at how their health was months and years later. Objective: To learn more about disease risks in relation to radiation from I-131 treatment for hyperthyroidism. Eligibility: People who were part of the previous study. These are people who were diagnosed with hyperthyroidism at U.S. and U.K. hospitals from 1946 to 1964. About 95% of the participants have already died. Design: Researchers will examine data already collected by the past study. This includes data on participants later cancers and other health outcomes after they had I-131 treatment. Researchers will compare that data to a National Death Index search. This was already done for data up through 2003. This study will cover 2004 2014. Researchers will not be in touch with study participants or their next of kin....

Hyperthyroidism (thyrotoxicosis) is a relatively common disease, especially among women, and radioiodine (I-131) administration is the treatment of choice for most adult patients. There is concern about possible carcinogenic effects of I-131 therapy, but previous studies of hyperthyroid patients have not presented clear results regarding cancer risks following I-131 treatment. There also is public concern regarding late health consequences of I-131 exposure as this radioiodine is one of the primary release products from nuclear power generation and a principal component in fallout from nuclear power plant accidents. The Thyrotoxicosis Therapy Follow-up Study (TTFUS) cohort, assembled in 1961, comprises 35,000 subjects treated for hyperthyroidism at over 20 medical centers in the US and one in Great Britain between 1946 and 1964. This is among the largest group of hyperthyroid patients that has been followed up for subsequent cancer and other health outcomes. The proposed mortality follow-up study will enable us to assess nearly lifetime risk of cancer and other diseases in this unique cohort. Mortality follow-up data will extend the observation through 2015, adding 15 more years, via linkage with the National Death Index search. Recently estimated I-131 radiation doses to various body organs will allow refined dose response analysis, providing most definitive assessment of the nature and magnitude of the risk of cancer and other disease associated with I-131 exposure as well as end-results of I-131 and other treatment for hyperthyroidism.