Hyperthyroid Follow-Up Study
Condition: All-Cause Mortality; Circulatory and Other Disease Mortality; Thyroid and Other Cancer Mortality
MeSH terms: Hyperthyroidism; Disease
Study type: Observational

Summary: 
      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....
    

Detailed description: 
      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.
    

Observational model: Cohort
Time perspective: Prospective
Sampling method: Non-Probability Sample
Study population: 
        The cohort includes all hypothyroid patients treated with I-131, thyroid surgery,
        anti-thyroid drugs, or any combinations of these treatments between 1946 and 1964 at 25
        U.S. and 1 UK institution. The cohort is largely female (79%), with a mean age at study
        entry (in 1961) of 46 years old. Hyperthyroidism patients in the cohort are classified as
        those with Graves disease (91%), toxic nodular goiter (8%), and unknown (1%).
      
Keywords: Hyperthyroidism; Radiation; Mortality