Friday, February 7, 2014

Seven More Confirmed Thyroid Cancer Cases: Total of 33 Cancer in Fukushima Children--A Synopsis of Results

Fourteenth Prefectural Oversight Committee convened on February 7, 2014, releasing the results of the latest thyroid examination as part of the prefectural health management survey.

English translation of the results is available here.


A summary of the results is provided below:

Total number of children examined as of December 31, 2013: 269,354

Total number of children whose initial examination results are confirmed: 254,280
(up to the November 15, 2013 examination)
     
     Assessment A1  134,805 (53.0%) (no nodules or cysts found)
     Assessment A2  117,679 (46.3%) (nodules 5.0 mm or smaller or cysts 20.0 mm or smaller)
     Assessment B     1,795 (0.7%) (nodules 5.1 mm or larger or cysts 20.1 mm or larger)
     Assessment C         1 (0.0%) (requiring immediate secondary examination)


Initial examination progress status



Number and proportion of nodules and cysts





Secondary examination includes more detailed thyroid ultrasound, blood and urine tests, and fine-needle aspiration biopsy if warranted.

      1,796 are eligible for secondary examination
      1,490 have actually undergone secondary examination
      1,342 finished the secondary examination

Secondary examination progress status




Summary of fine-needle aspiration biopsy results (as of December 31, 2013)






In summary, there were 7 more cancer cases confirmed since the last report on November 12, 2013. One case was confirmed in a female from Namie Town, 5 in Koriyama City, and 1 in Izumizaki Village. 

The total number of cases confirmed or suspected of cancer is 75. Of these, 34 had surgeries as of December 31, 2013, and 1 turned out to be a benign nodule, 32 were confirmed to be papillary thyroid cancer, and 1 still has no confirmed cytological diagnosis but listed as poorly differentiated thyroid cancer. (The total number of cases confirmed or suspected of cancer is often reported as 74 in news report, excluding the case confirmed to be benign).

Shinichi Suzuki, a Fukushima Medical University physician in charge of the thyroid ultrasound examination, cautioned against jumping to the conclusion about this "poorly differentiated cancer" which normally is associated with a poor prognosis. Although he did not elaborate on details, he said the diagnostic criteria for poorly differentiated thyroid cancer have recently changed. This was the case which, initially thought of as papillary thyroid cancer, was undergoing cytological reevaluation by pathologists who are still not sure about the exact subtype. 

Interestingly, the first thing Suzuki mentioned, when it was his turn to present the thyroid examination results at the committee meeting, was the news post published today in multiple newspapers regarding the Fukushima Medical University beginning a genetic analysis of the cancer tissues. The news post states that Fukushima Medical University will use the thyroid cancer tissues, excised during surgeries, to analyze for genetic alterations to help figure out why the cancer originated. What was odd was that Suzuki, as if avoiding a swarm of questions, offered an explanation that such genetic analyses are routinely performed on adult cancer specimen using the special research money and approved by the University's ethics committee. He emphasized that the genetic analysis was totally separate from the thyroid ultrasound examination. He asked for an understanding as he felt it was the mission of Fukushima Medical University to conduct the genetic analysis in order to watch over the children's future.

As for the perceived "slow" speed of confirming the cancer cases, Suzuki said that some of the cases suspected of cancer did not warrant immediate surgeries, allowing for the children to live their lives with close monitoring. 

As usual, no information was offered such as the type of nodules and also details of each surgical case which, as part of regular medical care, are considered beyond the scope of the screening and thus inaccessible to the Health Management Survey team.

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Below is a reference table showing the 2008 thyroid cancer incidence rate per 100,000 in Japan, compiled from the National Cancer Center (2012) Cancer incidence from cancer registries in Japan (1975–2007) on the website of Center for Cancer Control and Information Services, National Cancer Center, Japan. Due to an intense interest, domestically and internationally, in the pediatric thyroid cancer occurrence in Japan, the tables focused on the relevant age groups.

Thyroid cancer incidence rate in Japan by age and sex (2008) (per 100,000)
SourceDownload “2. Incidence (National estimates)” and go to the “rate” tab on bottom. 
See lines #1775 for male and #1809 for female.



This shows “incidence,” representing the rate of occurrence of new cases in a given period. On the other hand, Fukushima thyroid examination is mass screening, which yields “prevalence,” the proportion of the total number of cases to the total population.



It is important to note that incidence and prevalence are not directly comparable, so the incidence rates shown above are only a relative measure of comparison.