Recently, they have published the number of thyroid gland cancer cases in Fukushima. Surveying 174000 people aged less than 18 years with ultrasonography, 12 cases with the disorder were found. Fifteen cases are suspected for the disorder. This data itself won''t necessarily mean they are related with the irradiation at the accident since this kind of cancer is always latent in childhood. We need an age matched normal control study to be compared with them.
Last year, they have made control studies in the different areas away from Fukushima. They have studied 4000 cases for age matched control. The conclusion was that there were no differences in the frequency of cysts or nodules. In the other reports, nodular lesions could be regarded precancerous. This news has given us a bit of relief. But, for a normal control to research such rare disorder as thyroid cancer in this age group, the size is too small. They should extend the study to much more cases.
Unfortunately, they have not measured the I131 irradiation for a couple of weeks after the nuclear plant accident. I131 has rather short half life, so that it is not possible to measure the radiation dose for each of these patients at present. But they could estimate it for each case taking advantage of, for example, I127 in the soil etc. Estimated value of I131 irradiation dose should be published for each case. It may help us to guess any relationship between the disorder and the irradiation.
A few weeks ago, an organization of the UN has announced there could be least possibility to have cancer cases occur among those irradiated in Fukushima. It is just dependent on an estimation of irradiation. Not based on the real time measurement of irradiation. It is too early to conclude they could be spared for such a disorder.
It has been more than 2 years since the accident. It could be the time perilous for occuring throid gland cancer in childhood after irradiation.