Thyroid Ultrasound Examination: Outline of the Evaluations of the Results of the Preliminary Baseline Survey through to the Third Full-scale Survey (Fourth-round Survey)

In July 2023, the Thyroid Ultrasound Examination Evaluation Subcommittee, which was established under the Prefectural Oversight Committee for the Fukushima Health Management Survey, published the “Report on the Results of the Preliminary Baseline Survey through to the Third Full-scale Survey (Fourth-round Survey) of the Thyroid Ultrasound Examination.” In the Report, the Subcommittee presented its findings, based on the following results of the epidemiological analyses, that “no association is found between a detection rate of thyroid cancer in the Preliminary Baseline Survey through to the third Full-scale Survey and radiation exposure due to the accident.” The Subcommittee made a report on the findings at the Committee meeting held in November 2023.

• As a result of the analysis by the method of a cross-sectional survey using the estimated absorbed doses to the thyroid published in the report of the UNSCEAR, no constant correlation, such as an increase in detection rates of participants whose tumors were diagnosed as malignant or suspicious for malignancy associated with an increase in exposure doses (correlation between doses and effects), was found in any of the surveys.
• As a result of the analysis through case-control study regarding correlation between individual's estimated exposure dose and a diagnosis as being malignant or suspicious for malignancy, regarding thyroid cancer cases detected in the Preliminary Baseline Survey through to the third Full-scale Survey and thyroid cancer cases registered only in the cancer registry up to 2018, no constant correlation, such as an increase in detection rates associated with an increase in radiation exposure doses (correlation between doses and effects), was found.

• Included in this reference material on March 31, 2024