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Fukushima Thyroid Examination September 2016: 135 Thyroid Cancer Cases Confirmed (101 in the First Round and 34 in the Second Round)


135 Thyroid cancer cases confirmed in Fukushima as of June 30, 2016--101 in the first round and 34 in the second round (Total of 174 cases including suspected cancer cases--115 in the first round and 59 in the second round).


The 24th Prefectural Oversight Committee for Fukushima Health Management Survey convened in Fukushima City, Fukushima Prefecture, on Wednesday, September 14, 2016. 

Among other information, the Oversight Committee released the latest results (as of June 30, 2016) of the second round screening, which was conducted over a two-year period from April 2014 to March 2016. The second round screening is still ongoing in terms of the confirmatory examination, so the results are not complete.

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. 

Overview

As of June 30, 2016, there are 2 more cases with malignancy or suspicion of malignancy from the second round, for a total of 174 (175 including the single case of post-surgically confirmed benign nodule). The number of surgically confirmed cancer cases, excluding the aforementioned case of benign nodule, now totals 135 (101 from the first round and 34 from the second round), and the remaining 39 (14 from the first round and 25 from the second round) await surgical confirmation. 

Although the final results of the second round screening were widely anticipated at this Oversight Committee meeting, it turned out only two-thirds of those who were eligible for the confirmatory examination actually participated as of June 30, 2016. (Many of them might have undergone the confirmatory examination during the summer break, typically from late July through August).

Since the last results were released, only 4 additional cases from the second round have been operated on. Post-surgical pathological examination of the resected thyroid gland tissue confirmed 3 as papillary thyroid cancer and 1 as "other thyroid cancer" according to the classification in the seventh revision of Japan's unique thyroid cancer diagnostic guidelines released in November 2015.


Full-Scale Screening
To be conducted every 2 years until age 20 and every 5 years after age 20, the Full-Scale screening began with the second round screening in April 2014, including those who were born in the first year after the accident. There are 381,281 eligible individuals born between April 2, 1992 and April 1, 2012. As of June 30, 2016, 270,378 actually participated in the primary examination at the participation rate of 70.9% (lower than 81.7% at the first round screening). 270,327 have received confirmed results of the primary examination, and 2,217 (increased by 156 since the last Oversight Committee meeting) turned out to be eligible for the confirmatory examination. 

The confirmatory examination is still only about two-thirds complete. Of 1,476 who actually underwent the confirmatory examination, 1,379 received confirmed results including 176 that underwent fine-needle aspiration cytology (FNAC). FNAC revealed 59 cases suspicious for cancer. Confirmation of thyroid cancer requires pathological examination of the resected thyroid tissue obtained during surgery. As of June 30, 2016, 34 underwent surgery and 33 were confirmed to have papillary thyroid cancer. One remaining case was confirmed to have "other thyroid cancer" according to the classification in the seventh revision of Japan's unique thyroid cancer diagnostic guidelines. A specific diagnosis was not revealed, but Akira Ohtsuru, in charge of the thyroid screening, confirmed that it was a differentiated thyroid cancer that is not known to be related to radiation exposure.

Newly diagnosed cases in the second round
In the second round, 2 cases were newly diagnosed by FNAC to be malignant or suspicious of malignancy. They were 2 females (age at exposure: 12 and 14). Their places of residence at exposure were Iwaki City and Tadami Town, both of which are FY 2015 target municipalities.

In relation to the still ongoing confirmatory examination, special attention should be paid to the participation rate in Iwaki City. Of 45,228 Iwaki City residents who participated in the second round screening, 376 were eligible for the confirmatory examination. Only 172 have actually participated in the confirmatory examination as of June 30, 2016, and 134 of them have confirmed results. Thus, more confirmatory examination results are expected from Iwaki City, the largest of the FY2015 target municipalities. 

Prior diagnostic status of the cases newly diagnosed in the second round
Of 59 total cases with malignancy or suspicion of malignancy in the second round, 28 were A1, 26 were A2, and 5 were B in the first round.  

28 cases that were A1 in the first round screened suspicious for malignancy in the second round. This would appear to be a new onset after the first round since A1 cases by definition have no ultrasound findings of cysts or nodules.

In 26 cases that were A2 in the first round, 7 were nodules and 19 were cysts. (Two cases with malignancy or suspicion of malignancy reported this time are deduced to be A2 cysts in the first round). Thus the majority of the second round cases appeared to have developed thyroid cancer in 2 to 3 years since the first round. However, Ohtsuru explained this time that at certain ages in children, existing ultrasound lesions may not be visible until a few years later, suggesting there might have been invisible lesions in the first round which only became visible as the child aged.


First Round Screening (October 2011 - April 2015)
(This is the final results as of March 31, 2016. It is unchanged from the previous report).

Total number targeted: 367,672
Number of participants in primary examination: 300,476
Number with confirmed results: 300,476
  • A1   154,607 (51.5%) (no nodules or cysts found)
  • A2   143,575 (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)
(Note: Cysts with solid components are treated as nodules).

Number eligible for confirmatory (secondary) examination: 2,294
Number of participants in confirmatory (secondary) examination: 2,128
Number with confirmed results : 2,086
Number of fine-needle aspiration cytology (FNAC): 545
Number suspicious or confirmed of malignancy: 116 (including one case of benign nodules)

Number with confirmed tissue diagnosis after surgery: 102
  • 1 benign nodule
  • 100 papillary thyroid cancer
  • 1 poorly differentiated cancer


Second Round Screening (April 2014 - March 2016) (see report here)

Total number targeted: 381,281
Number of participants in primary examination: 270,378
Number with confirmed results: 270,327
  • A1   108,619 (40.2%) (no nodules or cysts found)
  • A2   159,491 (59.0%) (nodules ≦ 5.0 mm or cysts ≦ 20.0 mm)
  • B        2,217   (0.8%) (nodules ≧ 5.1 mm or cysts ≧ 20.1 mm)
  • C              0   (0.0%) (requiring immediate secondary examination)
(Note: Cysts with solid components are treated as nodules).

Number eligible for confirmatory (secondary) examination: 2,217
Number of participants in confirmatory examination: 1,476
Number with confirmed results: 1,379
Number of FNAB: 176
Number of cases with malignancy or suspicion of malignancy: 59
Number with confirmed tissue diagnosis after surgery: 34

  • 33 papillary thyroid cancer
  • 1 "other thyroid cancer"

Third Round Screening (May 2016 - March 2018) (see report here)

Total number targeted: 381,172
Number of participants in primary examination: 17,481
Number with confirmed results: 0




Unofficial translation of selected tables

Second Round Screening


Table 1. Primary examination coverage as of June 30, 2016

Table 2. Number and proportion of children with nodules/cysts as of June 30, 2016

Table 3. Participation rates by age group as of June 30, 2016

Table 4. Comparison with the Initial (Preliminary Baseline) Screening as of June 30, 2016

Note 1: Top line refers to the results of the Preliminary Baseline Screening for confirmed results of the Full-Scale Screening.

            It is not the breakdown of the total Preliminary Baseline Screening results, 300,476.

Note 2: Top line refers to the breakdown of the Full-Scale Screening results in a given category of the Preliminary Baseline Screening results. 

            Bottom line shows the proportion in %.

Table 5. Confirmatory testing coverage and results as of June 30, 2016

Table 6. Cytology results (including information from Appendix 6: Number of surgeries among cases with malignancy or suspicion of malignancy) as of June 30, 2016

Figure 3. Distribution of cases with malignancy or suspicion of malignancy by age (as of March 11, 2011) and sex (females in white and males in gray)


Figure 5.  Estimated external effective doses of those who submitted basic survey questionnaire as of June 30, 2016 (females in white and males in blue) 


Third Round Screening

Table 1. Primary examination coverage as of June 30, 2016


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