Medicine and Clinical Science

Tokyo’s sentinel surveillance weekly reporting highest record of Kawasaki disease cases in spring 2025 should be regarded as the key predictive indicator of a 2018-like situation, given Japan’s lack of rapid reporting of cancer incidence and the 2018 coincidence of extreme pollen levels with peak Kawasaki disease, cancer, and designated intractable disease incidence

Akira Awaya,

Akira Awaya

1) Dermatology & Epidemiology Research Institute (DERI), Yokohama, Kanagawa, Japan. 2) Graduate School of Nanobioscience, Yokohama City University, Yokohama, Kanagawa, Japan.

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Yoshiyuki Kuroiwa

Yoshiyuki Kuroiwa

1) Department of Neurology and Stroke Center, University Hospital Mizonokuchi, Teikyo University School of Medicine, Kawasaki, Kanagawa, Japan. 2) Department of Medical Office, Ministry of Finance, Japanese Government, Chiyoda-ku, Tokyo, Japan. 3) Department of Neurology, Yokohama City University Graduate School of Medical Sciences, Kanazawa-ku, Yokohama, Japan.

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  10.33425/2690-5191.1157
Background: The year 2018, seven years after 2011—which saw the second-highest pollen count in Tokyo's recorded history—was once again the year with the highest pollen count. The number of Kawasaki disease (KD) patients nationwide showed only a slight difference between 2018 (17,364) and 2019 (17,347). 2018 also marked the year with the highest number of KD cases in the nation's history, ranking first or second among all recorded years. The number of new cancer cases across all cancer types was also very close when comparing the two years of 2018 (over 980,000 people) and 2019 (just under 1 million people). 2018 saw the highest number of new cancer cases ever recorded across all cancer types, coinciding with the increase in KD incidence. It was also reported that the total number of registered designated intractable diseases also showed a continuous increase in 2018, with over 910,000 people in fiscal year 2018, nearly 950,000 in fiscal year 2019, and over 1.03 million in fiscal year 2020. Methods: According to the 2025 Tokyo Metropolitan Government sentinel surveillance weekly report on KD, the cumulative total of 117 KD cases reported through Week 22 significantly exceeded the 90 cases reported through Week 22 in 2018. The cumulative total of 243 KD cases reported through Week 47 of 2025 significantly exceeded the 191 cases reported through Week 47 of 2018. As mentioned earlier, 2018 saw the highest number of new cancer cases across all cancer types and the highest number of registrations for all designated intractable diseases, both linked to the incidence of KD. Results: Therefore, it is predicted that the number of new cancer cases across all cancer types and the number of registrations for all designated intractable diseases in 2025 will also reach record highs, linked to the incidence of KD. Furthermore, it is predicted that the number of new cases of cancer and designated intractable diseases will increase this year (2025), next year (2026), and the year after (2027). Conclusions: Will the Tokyo Metropolitan Government sentinel surveillance weekly report on KD in infants and young children serve as the sole means, indicator, or benchmark capable of predicting the magnitude of designated intractable diseases and cancer incidence this year, next year, and the year after? Otherwise, we request that at least the preliminary figures for cancer incidence in 2022, 2023, and 2024 be released as soon as possible.
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