Among other information, the Oversight Committee released the latest results of thyroid examination, consisting of Initial Screening or the first round screening (originally scheduled to be conducted from October 2011 to March 2014, and essentially completed as of April 30, 2015 with some confirmatory examination results pending) and Full-Scale Screening or the second round screening (from April 2014 to March 2016). It has been a little over 3 months since the last committee meeting on May 19, 2015, and the latest results include 3 more months worth of data confirmed as of June 30, 2015.
An official English translation of the results is available here. The narrative below contains some information gathered from the live webcast of the Oversight Committee meeting and the subsequent press conference.
As of June 30, 2015, there are 11 more (1 from the first round and 10 from the second round) malignant or suspicious cases, for a total of 137 (138 including the single case of post-surgically confirmed benign nodule). The number of surgically confirmed cancer cases, excluding the case of benign nodule, now totals 104 (98 from the first round and 6 from the second-round), and the remaining 32 more await surgical confirmation. Since the last results were released, only 1 case has been operated on. This may be due to the patients scheduling surgeries during school breaks.
Initial Screening (the first round screening) targeted about 368,000 individuals who were age 18 or younger, residing in Fukushima Prefecture at the time of the Tokyo Electric Fukushima Daiichi nuclear power plant accident on March 11, 2011.
Full-Scale Screening (the second round screening), to be conducted every 2 years until age 20 and every 5 years after age 20, additionally targets those who were born in the first year after the accident, aiming to examine approximately 385,000 individuals in a 2-year period.
A female from Iwaki City, age 16 at the time of the March 2011 accident (i.e. at exposure), was the newly diagnosed suspicious/malignant case from the first round. Confirmatory examination from the first round has 48 cases with pending results. It is possible there may be more suspicious/malignant cases from these 48 cases.
In the second round, 10 cases were newly diagnosed to be malignant/suspicious including 5 males (age at exposure: 10, 14, 15, 17 and 18) and 5 females (age at exposure: 9,11,13,13,13). Their places of residence at exposure include 7 municipalities: FY 2011 target municipalities such as Namie Town, Minamisoma City, and Date City (3 cases); and FY 2012 target municipalities such as Fukushima City (2 cases), Motomiya City, Koriyama City, and Kori Town.
Of the 25 suspicious/malignant cases in the second round, 10 were A1, 13 were A2, and 2 were B in the first round. (Of the newly diagnosed 10 cases, 2 were A1, 7 were A2, and 1 was B in the first round). Dr. Kazuo Shimizu, a thyroid surgeon and one of the committee members, was concerned whether these 10 A1 and 13 A2 cases might have had lesions which were missed (i.e. missed diagnosis) in the first round. If they weren't missed diagnoses, that means either the first round lesions became cancerous or cancer appeared newly since the first round. In the previously A1 cases, cancer most likely appeared newly as by definition A1 had no ultrasound findings. The question is how many of the 13 A2 cases might have developed new lesions since the last screening: if the A2 diagnosis was for nodules, they could have been precancerous lesions, but cysts are usually not expected to turn cancerous unless there was a solid component within (cysts with solid components are considered nodules in the Fukushima thyroid examination protocol). According to Dr. Akira Otsuru, director of the thyroid ultrasound examination, none of the cases had missed diagnoses in the first round, and 2 of the 13 A2 cases were nodules, with the remaining 11 being cysts. This means 21 (10 A1 and 11 A2 with cysts) cases had new suspicious/malignant lesions develop in the last 2-3 years since the first round screening.
As for the 2 cases which previously were diagnosed with B assessment, Dr. Otsuru would not answer, citing protection of patient privacy, whether they underwent the fine-needle aspiration biopsy/cytology in the first round.
In regards to the information sheet called Regarding Surgically Indicated Cases (for an English translation, see this post; the previous version can be seen here) submitted by Dr. Shinichi Suzuki, a thyroid surgeon at Fukushima Medical University and former director of thyroid ultrasound examination, a question was raised during the press conference as to whether the suspicious/malignant cases were overdiagnosed and/or overtreated. Dr. Kazuo Shimzu said that he felt that the fact 39% had extrathyroidal extension (pEX1 by the Japanese thyroid cancer diagnostic classification guideline; equivalent to T3) and only 8% showed no lymph node metastasis meant surgeries were conducted appropriately.
Fukushima Prefecture officials introduced a medical expense reimbursement program and a research study plan on the effect of radiation exposure, organized by the prefecture and commissioned to Fukushima Medical University.
The medical expense reimbursement program was implemented in order to cover out-of-pocket expenses for the residents who were diagnosed, as a result of the confirmatory examination, with thyroid cancer or other thyroid conditions requiring regular medical follow-up. Unlike the ultrasound screening examination which bears no cost to the participants, the treatment (clinical) phase of the thyroid examination shifts to regular medical care using the national health insurance system, incurring a copay of 20-30%. Fukushima residents 18 or younger (or more accurately, until March 31 once they turn 18) receive free medical care covering the copay, but in the beginning of a new fiscal year after they turn 18, they will be responsible for the 30% copay. As 63 of 112 suspicious/malignant cases in the first round are 18 or older at diagnosis, the undue financial burden on them and their families has been an issue. The Fukushima Prefectural assembly has approved the medical expense reimbursement program to offer a financial relief to the 900-1000 eligible residents. (Note: This does not mean the prefecture expects all of these 900-1000 residents to get cancer as it was speculated when the news first came out with incomplete details. Some have conditions/lesion -- no specifics released -- which happened to have been discovered during the screening).
A research project currently being considered is on the estimation of the expected number of suspicious/malignant cases in Initial Screening from a model of thyroid tumor progression based on the national incidence data on thyroid cancer. The project team will include Fukushima Medical University, Osaka University, Nagoya University, and Radiation Effect Research Foundation, and the findings will be written up and promptly reported to the Oversight Committee.
It appears that the Fukushima Prefectural government is trying to take control of how the Fukushima Health Management Survey data is used, as Fukushima Medical University stays busy publishing a multitude of studies based on the data while failing to disclose relevant information in a transparent manner.
There was also a suggestion from a committee member, Dr. Fumiko Kasuga from National Institute of Health Sciences, to replace the often used phrase, "XX is unlikely to be due to the effect of radiation exposure" with something like, "A small possibility cannot be denied that XX is due to the effect of radiation exposure."
A summary of the results are provided below for Initial Screening and Full-Scale Screening, followed by unofficial translation of selective tables from the results. All numbers shown below are from the data analysis as of June 30, 2015.
Total number targeted: 367,685
Number of participants in primary examination: 300,476
Number with confirmed results: 300,476
- A1 154,606 (51.5%) (no nodules or cysts found)
- A2 143,576 (47.8%) (nodules ≦ 5.0 mm or cysts ≦ 20.0 mm)
- B 2,293 (0.8%) (nodules ≧ 5.1 mm or cysts ≧ 20.1 mm)
- C 1 (0.0%) (requiring immediate secondary examination)
- 1 benign nodule
- 95 papillary thyroid cancer
- 3 poorly differentiated cancer
- A1 63,884 (41.6%) (no nodules or cysts found)
- A2 88,570 (57.6%) (nodules ≦ 5.0 mm or cysts ≦ 20.0 mm)
- B 1,223 (0.8%) (nodules ≧ 5.1 mm or cysts ≧ 20.1 mm)
- C 0 (0.0%) (requiring immediate secondary examination)
- 6 papillary thyroid cancer
Unofficial translation of selected tables
Table 1. Primary examination results (final results from October 9, 2011 to April 30, 2015)
Table 4. Cytology results (including information from Appendix 7: Surgical cases of suspicious or malignant cases)
Table 1. Primary examination coverage as of June 30, 2015