Fukushima Thyroid Examination September 2018: 164 Surgically Confirmed as Thyroid Cancer Among 201 Cytology Suspected Cases

For more detailed information on the Fukushima Thyroid Examination itself, see the September 2017 fact sheet (long version, or e-published PDF)

Highlights: 

• The third round: 3 cases newly diagnosed as suspicious or malignant, and 2 new  cases surgically confirmed.
• The fourth round began on April 1, 2018.
• Total number of suspected/confirmed thyroid cancer is now 201 (excluding a single case of benign tumor; 115 in the first round, 71 in the second round, and 15 in the third round).
• Total number of surgically confirmed thyroid cancer cases has increased by 2 to 164 (101 in the first round, 52 in the second round, and 11 in the third round)

The latest overall results:

(Scroll down for the latest results including the "unreported" cases explained in this post.)

On September 5, 2018, the 32nd Oversight Committee for Fukushima Health Management Survey (FHMS) convened in Fukushima City, Fukushima Prefecture. Among other information, the Oversight Committee released the latest results (as of June 30, 2018) of the third and fourth rounds of the Thyroid Ultrasound Examination (TUE). 

A four-page summary of the first through third rounds, "The Status of the Thyroid Ultrasound Examination," was also released, listing key findings from the primary and confirmatory examinations as well as the surgical information. In particular, any update to the number of surgical cases is reflected in this summary before such information is compiled in the fiscal year update as of March 31. This summary is not translated into English officially, but here's an unofficial translation. 

Status of the Thyroid Ultrasound Examination (September 5, 2018) by Yuri Hiranuma on Scribd

Key points from the Oversight Committee:

Target population shrinks
For the fourth round to be conducted during FY2018-2019, the target population excludes about 44,000 individuals total (22,000 each from FY2018 and FY2019) as those born in FY1993 and FY1994 will shift to the Age 25 Milestone Screening in FY2018 and FY2019, respectively).

The first Age 25 Milestone Screening results for those born in FY1992 were released at the last Oversight Committee meeting on June 18, 2018. Only 1,902 out of 22,653 participated at a strikingly low participation rate of 8.4%. It should be noted that with each successive round of screening, more and more individuals reaching age 25 will be removed from the main dataset. So far no thyroid cancer has been diagnosed in the Milestone Screening cohort, but any cancer case from this cohort will not be reflected in the age distribution graphs of the main dataset. 

For each round, there are two such graphs: one for age-at-exposure as of March 11, 2011 and the other for age-at-examination. Because thyroid cancer incidence naturally increases with age, one would expect a growing trend towards the right in the age distribution graph. The second round age-at-exposure graph, before the Age 25 Milestone Screening began, lacks this trend and falls to the right, most likely due to a lower participating rate beyond the high school age. The third round age-at-exposure graph completely deviates from an expected pattern, mostly blank in higher ages saving 2 cases at age-at-exposure of 16 years. This likely reflects even a lower participation rate after high school graduation, in addition to the exclusion of those eligible for the Age 25 Milestone Screening. An appearance of no cancer cases for higher ages might simply be an artifact due to exclusion of individuals reaching age 25.

Participation rates

The primary examination participation rates have been declining with each successive round of the TUE: 81.7% for the first round, 71.0% for the second round, and 64.3% for the third round. In particular, a participation rate for age 18 or older (age at examination) has gone from already low 25.7% in the second round to even lower 15.9% in the third round.  

Participation rates for the confirmatory examination have also been declining from 92.9% in the first round, 84.1% in the second round, and 58.7% in the third round which is still ongoing.

Correction of the number of surgeries conducted outside FMU

At this committee meeting, a discrepancy in the number of surgical cases at medical facilities other than FMU (refereed to as "non-FMU surgical cases" herein) was resolved.

So far clinicopathological information on surgical cases have been released three times: as a document called "Regarding Surgical Indicated Cases" in November 2014 (at the 4th Thyroid Examination Assessment Subcommittee) and August 2015 (at the 20th Oversight Committee); and presented at an international symposium in September 2016. (Note
the 2016 information was later reported as "Regarding Surgical Indicated Cases" at the 8th Thyroid Examination Assessment Subcommittee in November 2017. This means and no new clinical information has been reported to the Oversight Committee since 2016.) 

Information released so far shows the number of surgeries conducted at non-FMU facilities as 3, 7, and 6 in 2014, 2015, and 2016, respectively. It is easy to see the number increased from 3 to 7 from 2014 to 2015 as the number of surgical cases increased. However a drop from 7 to 6 has been a mystery. 

A closer look at the 2016 number shows that there were 132 surgical cases between August 2012 and March 2016 (see Slide 1 in this post). Of 132, 126 surgeries were conducted at FMU, and one was diagnosed benign and 125 malignant. Non-FMU surgical cases are shown as 6. However, it turns out that 126 surgical cases included one case operated on in April 2016. The TUE data is compiled fiscally, with the end of a fiscal year being March 31 of the following calendar year. Thus, strictly speaking, 125 of 132 surgeries as of March 31, 2016 were conducted at FMU resulting in one benign and 124 malignant cases, leaving non-FMU surgical cases at 7, not 6 as previously reported. 

However, this creates another discrepancy because Slide 2 of this post discusses "Characteristics of 125 thyroid cancers at Fukushima Medical University", not 124. This was resolved in the correction report (only in Japanese) which explained that the clinicopathological details given on 125 FMU surgical cases includes the April 2016 case.
   
Non-FMU surgical cases have not been kept track of
In relation to the above corrections, Hiroki Shimura, head of the TUE program, revealed that FMU has not kept track of non-FMU surgical cases beyond the 7 cases already reported. Shimura explained that the surgical information as clinical information is outside the scope of the TUE, but it has been reported out of courtesy. However, FMU began to report the number of surgical cases on the last page of the report, separately from the rest of the results such as cytology results at the 19th Oversight Committee in May 2015. Up to this point, surgical information was included in the cytology results section. Their intention appears to be to clarify what belongs to the TUE itself. 

Shimura further explained that during the first round and part of the second round (probably through March 2016), non-FMU surgical cases were included in the number of surgeries reported to the Oversight Committee. However, beyond 7 non-FMU surgical cases already reported, FMU has not attempted or does not intend to kept track of non-surgical cases. 

The reason given by Shimura has to do with FMU's decision to tighten how clinical information is obtained and released, reflecting "changes in how the society views research ethics and patient privacy protection." Shimura elaborated that FMU has been careful about whether or not to obtain clinical information from other medical facilities, giving a special consideration to release of information that might reveal patient identity and to appropriate ethics review. In regard to obtaining non-FMU surgical data, Shimura cites a potential difficulty in  confirming authenticity of such data as well as a lack of actual mechanism to  follow patients outside the FMU system.

This revelation was a surprise. FMU has no idea if and how many surgeries might be conducted outside FMU including medical facilities contracted to participate in the TUE. Not all medical facilities contracted to conduct the primary and confirmatory examinations may offer surgeries, but they already have a line of communication established with FMU in order to send the raw data. Rather than trying everything possible to gather all the data available, FMU appears to be making excuses not to add to their dataset.

This revelation also brings a doubt on accuracy of the number of cases suspected of thyroid cancer which have not undergone surgery. There are 37 such cases as of June 30, 2018: 14 from the first round, 19 from the second round, and 4 from the third round. It is possible that these 37 cases are simply being followed up regularly without needing any surgery, but it is also plausible that some, especially from the first and second rounds which have been followed up quite some time, might have already undergone surgery outside FMU.

Reluctance on releasing detailed data

There have been repeated requests to FMU from multiple committee members to release more detailed data. Fumiko Kasuga, a committee member from the National Institute of Health Sciences, again asked for a more detailed breakdown of tumor sizes in cancer patients and reiterated that information gained from the TUE belongs to Fukushima residents and that any data should be shared with the residents in an easy-to-understand manner. 

However, detailed data are often presented at academic meetings or released in academic publications first, without ever being reported to the Oversight Committee. Clinical details of surgical cases are one such example: no new data beyond the 132 surgical cases as of March 2016 has been reported to the Oversight Committee or the Subcommittee, while more recent data on 153 surgical cases (including 145 FMU cases) as of March 2017 were presented at the Japan Thyroid Association meeting in October 2017. As shown in the abstract below, it appears that the same data are to be presented at the poster session during the 88th Annual Meeting of the American Thyroid Association in October 3-7, 2018. (Abstracts can be seen here.)

  

Furthermore, FMU's partial analysis of some of the first and second round data (available only in Japanese here) released at the 10th Thyroid Examination Assessment Subcommittee meeting on July 8, 2018 met a near unanimous request from the subcommittee members to make data available in actual numbers rather than just percentages (the minutes of the proceedings are available here in Japanese). At the time, FMU officials asserted as before that detailed information were not to be released for the protection of patient privacy. 

Shimura also explained that a more detailed analysis considering various biases could breakdown the data into very small sample sizes, such as one or two cases, potentially revealing their identity. Some subcommittee members emphasized the need for seeing actual data in order to begin some type of analysis. FMU officials expressed their willingness to share actual data with subcommittee members in a closed meeting, especially with those specializing in epidemiology.

During this Oversight Committee meeting, Tamami Umeda, a committee member representing the Ministry of the Environment stressed an importance of sharing data with transparency. Umeda also repeated her previous request to integrate all the data available, including data from the TUE support program and the unreported cases clinically and surgically managed at FMU (see the post on the previous Oversight Committee meeting here). Kasuga also made a similar request.

The latest overall results including "unreported" cases
Here's the latest results including unreported cases. It should be kept in mind that even this table is far from being comprehensive: the TUE support program data isn't detailed enough to be included in this format, and there are surgical cases from other medical facilities completely outside the framework of the TUE. (The italicized part was added on October 2, 2018)

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The first round results (no change from the previous report)

From the FY 2016 supplemental report with data as of March 31, 2017. (Summary report with data as of March 31, 2018, only shows the total results, not by fiscal year cohorts. However, for the content shown below, information remained the same between 2017 and 2018.)

The second round results 

No change since the March 5, 2018 Oversight Committee meeting.

The third round results

Three new suspicious/malignant cases were diagnosed, all from the FY 2017 cohort: two females (ages 10 and 11 in March 2011) and 1 male (age 9 in March 2011). One resides in a Hama-dori municipality, and the other two in the Aizu region. All three were assessed "B" in the second round.