Picture of Ryuki KassaiRyuki Kassai is a founding professor and chair of the Department of Community and Family Medicine at Fukushima Medical University, Fukushima, Japan

One day in November 2013, a 14-year-old girl came with her mother to my clinic in Koriyama, Fukushima. She complained of one-week history of sore throat and hoarseness. Disease specific history and physical examination revealed nothing particular except for a little husky voice. Then I asked her about her life and any recent change of it. She said she was a member of her school chorus busy practising for the year-end concert. I was about to conclude that she might have overused the throat, or had a mild cold perhaps. But, her mother then asked me if she really had a thyroid cancer, because she had received the result letter of the preliminary thyroid ultrasound examinations a week before, which reported that she had an A2 lesion of the thyroid.

Koriyama city has a long and brilliant history of the chorus. Many schoolgirls and schoolboys are proud to be members of their school chorus, which have won the championship at the annual national contests many times. The Great East Japan Earthquake hit the city, which is located 60 km west of the Pacific coast and the tsunami-hit Fukushima Daiichi nuclear power plant, heavily on 11 March 2011 and thereafter. Air radiation level in Koriyama has been less than 0.25 microSv/hr.

In October 2011, Fukushima prefecture government started preliminary thyroid ultrasound examinations as a surveillance programme for all the prefecture children younger than 18 years old (approximately 360,000 children). As of December 2013, 269,354 children have had the first examinations; of these, 33 children were diagnosed with thyroid cancer (32 papillary carcinoma and 1 suspected poorly differentiated carcinoma), and 41 have a suspicion of thyroid malignancy. The ages of those children with thyroid cancer or its suspicion were 16.9±2.6 years old. The Chernobyl accident resulted in an increase in thyroid cancer incidence 4 to 5 years after exposure. Younger children are at higher risk than older children. Internal exposure is thought to have played a major role in carcinogenesis in Chernobyl, which will not be the case in Fukushima because of the prefecture’s earlier initiation of food inspection to detect radioactive contamination.

Should we call this rate of discovery of thyroid cancer (33/269,354 = 12/100,000), incidence, or prevalence? Since thyroid cancers progress slowly, this rate for the children 0-18 years old may almost be equivalent to an annual incidence of 0.67 (= 12/18) per 100,000, which is only slightly higher than the ones reported previously, such as 0.54 per 100,000 in the SEER registry in the US [Hogan AR, et al. J Surg Res. 2009; 156(1):167-72.].

The A2 lesions, which my patient was reported to have, consist of thyroid cysts smaller than 20.0 mm in diameter, and nodules smaller than 5.0 mm in diameter. Based on the best available evidence, we consider it no malignancy and warrant no urgent further investigation. As of December 2013, 117,679 children out of 269,354 Fukushima children examined had the A2 lesions (43.7%).

Generally speaking, people in Fukushima are of resilient and endurant nature. But we have often been annoyed and devastated by abundant noise of information through a wide variety of sources, from the mass media to the social network services. Intentionally or through being uninformed, most of them tend to make no distinction between incidence and prevalence, and regard the A2 lesion a kind of malignancy. My middle school patient and her mother had actually been so scared of finding out that she had a thyroid cancer. She said to me, “Before coming here I was afraid I won’t be able to sing songs anymore.”

Unfortunately sound scientific explanation of safety is often wrongly regarded as concealment of the truth when it is announced to the public. Sadly, distrust is everywhere in Japan, for now. In addition, there is a criticism that the surveillance programmes of Fukushima after the nuclear disaster in 2011 can lead to overdiagnosis and medicalisation. This could be true and reasonable, but how could we ignore very anxious people who have to live under an uncertain situation in Fukushima for such a long time? I believe that an individualised patient-centered approach and continuity of care for the people of Fukushima is the best way forward to complement efforts at ensuring their healthy life.

Ryuki Kassai, MD, PhD, MRCGP