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Childhood Thyroid Cancer in Russia Following the Chernobyl accident

Medical Radiological Research Center National Radiation and Epidemiological Registry. Childhood Thyroid Cancer in Russia Following the Chernobyl accident. V.K. Ivanov Chairman, Russian Scientific Commission on Radiological Protection.

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Childhood Thyroid Cancer in Russia Following the Chernobyl accident

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  1. Medical Radiological Research Center National Radiation and Epidemiological Registry Childhood Thyroid Cancer in Russia Following the Chernobyl accident V.K.Ivanov Chairman, Russian Scientific Commission on Radiological Protection The International Workshop on Radiation and Thyroid Cancer Japanese Ministry of the Environment (MoE) Fukushima Medical University (FMU)The OECD Nuclear Energy Agency (NEA) Tokyo, Japan, 21-23 February 2014

  2. Questions… Increased thyroid cancer incidence in residents exposed to radiation following the Chernobyl accident in their childhood  Why… & How estimate…? Increase in background (non-radiation) thyroid cancer incidence + radiation-induced thyroid cancer incidence Estimating RADIATION RISK Estimating SCREENING EFFECT

  3. NRER IS A PART OF MEDICAL RADIOLOGICAL RESEARCH CENTER OF THE RUSSIAN MINISTRY OF HEALTH NATIONAL RADIATION AND EPIDEMIOLOGICAL REGISTRY 23 regional centers 4 000 hospitalsand clinics 798 000 registered persons 400 000 Individual doses 18 000 000 diagnoses The National Registry is the WHO Collaborating Centre for Research and Training in Radiation Epidemiology STRUCTURE OF THE REGISTERED PERSONS

  4. COHORT SELECTED • FOR ANALYSIS OF RADIATION RISK OF THYROID CANCER • Size of Cohort:309,130individuals with known thyroid dose • (people living in contaminated areas137Cs ≥ 5 Ci/km2) • Bryansk, Kaluga, Orel and Tula regions • Follow-up period: registration of persons Start of follow-up End of follow-up 18 years 1986 1991 1980 2008 • Cases:993 Thyroid cancers (ICD-10: C73)

  5. AVERAGE THYROID DOSES IN THE SETTLEMENTS OF BRYANSK, KALUGA, OREL AND TULA OBLASTS The individualized thyroid doses for cohort members have been defined as equal to the average age-specific thyroid doses in their settlements at 1986, according to the Russian official catalogue of average doses of exposure of the thyroid gland. Ivanov VK, KashcheevVV et al. RadiatProt Dosimetry; 2012 Sep;151(3):489-99.

  6. METHODS: Excess relative risk (ERR) model – observed increase in thyroid cancer incidence rate 0 – baseline thyroid cancer incidence rate ERR– excess relative risk per 1 Gy d– average absorbed dose for the thyroid gland

  7. METHODS: Baseline thyroid cancer incidence rate 0rus– thyroid cancer incidence rate in Russia SIR– standardized incidence ratio (SCREENING EFFECT)

  8. Thyroid dose, Gy • METHODS: Assessment of screening and dose response ERR (dose response) SCREENING EFFECT

  9. SIR AND ERR OF THYROID CANCER IN REGISTERED POPULATION OF BRYANSK, KALUGA, OREL AND TULA OBLASTS Cohort:309,130individuals (993 cases of thyroid cancer)

  10. SIR AND ERR OF THYROID CANCER AMONG CHILDREN AND ADOLESCENTS (0-17 y in 1986) Sub-Cohort:97,191 individuals (247cases of thyroid cancer)

  11. RELATIVE RISK OF THYROID CANCER AMONG CHILDREN AND ADOLESCENTS (in 1986) BY DOSE GROUPS Model of Relative Risk:

  12. RELATIVE RISK OF THYROID CANCER AMONG CHILDREN AND ADOLESCENTS (0-17 y in 1986) BY DOSE GROUPS Internal control: 0-50 mGy * Dashed line is RR=1+ERR, where ERR (3.58, 95% CI:1.61-5.57)

  13. EXPANDED STUDY OF SCREENING EFFECT AND RADIATION RISK OF THYROID CANCER Cohort of children and adolescents:97,191persons (0-17 y in 1986) (people living in contaminated areas 137Cs ≥ 5 Ci/km2) Extended Follow-up period: registration of persons End of follow-up Start of follow-up 21 years 1986 1991 1980 2008 2011 + 25 cases = 272 Cases:247 Thyroid cancers (ICD-10: C73)  Tasks… • SCREENING EFFECTas the function of time • Dose-response in low-dose range (< 250 mGy)

  14. INCIDENCE RATE OF THYROID CANCER IN MALE POPULATION OF THE RUSSIAN FEDERATION

  15. INCIDENCE RATE OF THYROID CANCER IN FEMALE POPULATION OF RUSSIAN FEDERATION sex-ratio incidence:

  16. OBSERVED AND EXPECTED NUMBER OF THYROID CANCER CASES AMONG CHILDREN AND ADOLESCENTS (0-17 y. in 1986) BY CALENDAR PERIODS

  17. SIR OF THYROID CANCER AMONG CHILDREN AND ADOLESCENTS AS A FUNCTION OF CALENDAR PERIOD IMPORTANT!SIR includes the radiation risk => SIR ≠ SCREENING

  18. NEW ANALYSIS OF SIR AND ERR OF THYROID CANCER AMONG CHILDREN AND ADOLESCENTS • Cohort of children and adolescents:97,191persons • 272 cases of thyroid cancer

  19. NEW ANALYSIS OF SIR AND ERR OF THYROID CANCER AMONG CHILDREN AND ADOLESCENTS • Cohort of children and adolescents:97,191persons • 272 cases of thyroid cancer

  20. NEW ANALYSIS OF SIR AND ERR OF THYROID CANCER AMONG CHILDREN AND ADOLESCENTS • Cohort of children and adolescents:97,191persons • 272 cases of thyroid cancer (PURE EFFECT)

  21. THYROID CANCER RISK AMONG CHILDREN AND ADOLESCENTS (BOTH SEXES) IN LOW-DOSE RANGE • Cohort of children and adolescents:97,191persons • 272 cases of thyroid cancer

  22. FITTED ATTRIBUTABLE RISK OF THYROID CANCER (BOTH SEXES) AS A FUNCTION OF AGE AT EXPOSURE radiation-induced cases Attributable risk = radiation-induced cases + spontaneous cases х 100 %

  23. CONCLUSION Statistically significant SCREENING EFFECT on thyroid cancer incidence was detected in people lived in radioactively contaminated territories following the Chernobyl accident. The SCREENING EFFECT depends on calendar period of follow-up. The highest value of SIR (15.2 95% CI: 10.6; 20.9) was observed in the earliest follow-up period, from 1991 to 1995. Statistically significant radiation risk of thyroid cancer is for children and adolescents (0-17 years at the time of exposure) only . Statistically significant radiation risk of thyroid cancer is associated with thyroid doses > 250 mGy. Data on Chernobyl are useful for estimating long-term radiological effects following the accident at the Fukushima-1 NPP.

  24. Thank you for your attention

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