Childhood Thyroid Cancer in Russia Following the Chernobyl accident V.K. Ivanov Chairman, Russian...
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Transcript of Childhood Thyroid Cancer in Russia Following the Chernobyl accident V.K. Ivanov Chairman, Russian...
Childhood Thyroid Cancer in Russia Following the Chernobyl accident
V.K. IvanovChairman, Russian Scientific Commission on Radiological Protection
Medical Radiological Research Center National Radiation and Epidemiological Registry
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
Questions… Increased thyroid cancer incidence in residents exposed to radiation following the Chernobyl accident in their childhood
Increase in background(non-radiation)
thyroid cancer incidence
radiation-inducedthyroid cancer incidence +
EstimatingSCREENING EFFECT
EstimatingRADIATION RISK
Why… & How estimate…?
NRER IS A PART OF MEDICAL RADIOLOGICAL RESEARCH CENTER OF
THE RUSSIAN MINISTRY OF HEALTH
The National Registry is the WHO Collaborating Centre for Research and Training in Radiation Epidemiology
23 regional centers4 000 hospitals and clinics
798 000 registered persons400 000 Individual doses
18 000 000 diagnoses
NATIONAL RADIATION AND EPIDEMIOLOGICAL REGISTRY
STRUCTURE OF THE REGISTERED PERSONS
COHORT SELECTED FOR ANALYSIS OF RADIATION RISK OF THYROID CANCERSize of Cohort: 309,130 individuals with known thyroid dose (people living in contaminated areas 137Cs ≥ 5 Ci/km2) Bryansk, Kaluga, Orel and Tula regions
1980 1986 1991 2008
registrationof persons
Start of follow-up
End of follow-up18 years
Follow-up period:
Age at exposure (1986), y
Registered persons
Observed cases
N % N
0-17 97,191 31 % 247
18 + 211,939 69 % 746
Total 309,130 100 % 993
Cases: 993 Thyroid cancers (ICD-10: C73)
AVERAGE THYROID DOSES IN THE SETTLEMENTS OF BRYANSK, KALUGA, OREL AND TULA OBLASTS
Ivanov VK, Kashcheev VV et al. Radiat Prot Dosimetry; 2012 Sep;151(3):489-99.
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.
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
,dERR 10
METHODS:
Baseline thyroid cancer incidence rate
0rus – thyroid cancer incidence rate in Russia
SIR – standardized incidence ratio (SCREENING EFFECT)
SIRrus 00
Expected
ObservedSIR
METHODS:
Assessment of screening and dose response
Thyroid dose, Gy
SCREENING EFFECT
ERR (dose response)
,dERRSIRrus 10
SIRrus 0
rus0
Follow-up: 1991 – 2008Age at the time of the Chernobyl accident (years)
0-17 y 18 y and older
Number of persons 97,191 211,939
Number of cases 247 746
Mean dose in healthy cohort members (mGy) 188 37
Mean dose in cases (mGy) 225 32
SIR, SCREENING EFFECT (95% CI), p-value 7.80 (5.95; 9.81), p<0.001 3.73 (3.42; 4.07), p<0.001
ERR per 1 Gy (95% CI), p-value 3.58 (1.61; 5.57), p<0.001 -0.49 (-2.33; 1.36), p>0.5
SIR AND ERR OF THYROID CANCER IN REGISTERED POPULATION OF BRYANSK, KALUGA, OREL AND TULA OBLASTS
Cohort: 309,130 individuals (993 cases of thyroid cancer)
Follow-up: 1991 – 2008Age at the time of the Chernobyl accident (years)
0-17 y (boys) 0-17 y (girls)
Number of persons 44,598 52,593
Number of cases 61 186
Mean dose in healthy cohort members (mGy) 178 196
Mean dose in cases (mGy) 250 218
SIR, SCREENING EFFECT (95% CI), p-value10.55 (4.59; 17.80), p<0.001
7.48 (5.58; 9.61), p<0.001
ERR per 1 Gy (95% CI), p-value 6.70 (1.88; 23.13), p<0.001 2.68 (0.66; 5.60), p<0.001
SIR AND ERR OF THYROID CANCER AMONG CHILDREN AND ADOLESCENTS (0-17 y in 1986)
Sub-Cohort: 97,191 individuals (247 cases of thyroid cancer)
RELATIVE RISK OF THYROID CANCER AMONG CHILDREN AND ADOLESCENTS (in 1986) BY DOSE GROUPS
Dose group (mGy)
Mean dose (Gy)
Number of cases Person-years RR
(95% CI) p-value
0-0.05 0.027 49 288,218 1 (Reference)
0.05-0.1 0.072 53 318,536 1.01 (0.68; 1.49) > 0.5
0.1-0.15 0.124 37 212,491 1.18 (0.77; 1.81) 0.46
0.15-0.2 0.173 18 131,218 0.91 (0.52; 1.53) > 0.5
0.2-0.25 0.222 18 97,500 1.64 (0.93; 2.76) 0.085
0.25-0.3 0.273 16 75,420 2.15 (1.18; 3.69) 0.013
0.3-0.35 0.324 17 44,432 3.12 (1.75; 5.30) < 0.001
0.35-0.5 0.418 20 94,791 2.31 (1.35; 3.83) 0.003
> 0.5 0.860 19 107,504 2.40 (1.36; 4.03) 0.002
)( 00 irus DRRSIR Model of Relative Risk:
RELATIVE RISK OF THYROID CANCER AMONG CHILDREN AND ADOLESCENTS (0-17 y in 1986) BY DOSE GROUPS
0
1
2
3
4
5
6
0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1
Thyroid dose, Gy
RR
Internal control: 0-50 mGy
* Dashed line is RR=1+ERR, where ERR (3.58, 95% CI:1.61-5.57)
EXPANDED STUDY OF SCREENING EFFECT AND RADIATION RISK OF THYROID CANCER
Cohort of children and adolescents: 97,191 persons (0-17 y in 1986)(people living in contaminated areas 137Cs ≥ 5 Ci/km2)
1980 1986 1991 2008
registrationof persons
Start of follow-up
End of follow-up21 years
Extended Follow-up period:
Cases: 247 Thyroid cancers (ICD-10: C73)
2011
+ 25 cases = 272
Tasks… • SCREENING EFFECT as the function of time• Dose-response in low-dose range (< 250 mGy)
INCIDENCE RATE OF THYROID CANCER IN MALE POPULATION OF THE RUSSIAN FEDERATION
INCIDENCE RATE OF THYROID CANCER IN FEMALE POPULATION OF RUSSIAN FEDERATION
sex-ratio incidence:
OBSERVED AND EXPECTED NUMBER OF THYROID CANCER CASES AMONG CHILDREN AND ADOLESCENTS (0-17 y. in 1986)
BY CALENDAR PERIODS
SIR OF THYROID CANCER AMONG CHILDREN AND ADOLESCENTS AS A FUNCTION OF CALENDAR PERIOD
IMPORTANT! SIR includes the radiation risk => SIR ≠ SCREENING
Expected
ObservedSIR
Follow-up: 1991 – 20110-17 y at the time of the Chernobyl accident
published in RPD new analysis
Number of persons 97,191 97,191
Number of cases 247 272
Mean dose in healthy cohort members (mGy) 188 188
Mean dose in cases (mGy) 225 214
SIR, SCREENING EFFECT (95% CI), p-value 7.80 (5.95; 9.81), p<0.001 6.65 (5.15; 8.24), p<0.001
ERR per 1 Gy (95% CI), p-value 3.58 (1.61; 5.57), p<0.001 3.81 (1.81; 6.86), p<0.001
NEW ANALYSIS OF SIR AND ERR OF THYROID CANCER AMONG CHILDREN AND ADOLESCENTS
Cohort of children and adolescents: 97,191 persons 272 cases of thyroid cancer
Follow-up: 1991 – 20110-17 y at the time of the
Chernobyl accident
SCREENING EFFECT by periods, 95% CI
1991 – 1995 15.2 (10.6; 20.9)
1996 – 2000 7.5 (5.5; 9.9)
2001 – 2005 6.7 (5.1; 8.6)
2006 – 2011 7.0 (5.5; 8.8)
ERR per 1 Gy (95% CI), p-value 3.34 (1.39; 6.82), p<0.001
NEW ANALYSIS OF SIR AND ERR OF THYROID CANCER AMONG CHILDREN AND ADOLESCENTS
Cohort of children and adolescents: 97,191 persons 272 cases of thyroid cancer
NEW ANALYSIS OF SIR AND ERR OF THYROID CANCER AMONG CHILDREN AND ADOLESCENTS
Cohort of children and adolescents: 97,191 persons 272 cases of thyroid cancer
(PURE EFFECT)
Dose range,mGy
Average thyroid dose,
mGyCases
ERR per 1 Gy,(95% CI)
p-value
0 – 100 53.2 113 -2.99 (-6.76; 4.65) > 0.5
0 – 125 63.0 132 -1.63 (-4.82; 4.44) > 0.5
0 – 150 71.4 160 3.57 (-0.90; 12.3) 0.143
0 – 200 84.8 180 1.81 (-1.24; 7.25) 0.3
0 – 250 98.2 199 2.40 (-0.36; 7.18) 0.1
0 – 300 110.4 218 4.05 (1.09; 9.16) 0.003
0 – 500 139.6 253 5.15 (2.39; 9.73) < 0.001
0 – 1000 172.3 269 4.31 (2.16; 7.75) < 0.001
> 0 189.4 272 3.81 (1.81; 6.86) < 0.001
THYROID CANCER RISK AMONG CHILDREN AND ADOLESCENTS (BOTH SEXES)
IN LOW-DOSE RANGE Cohort of children and adolescents: 97,191 persons
272 cases of thyroid cancer
FITTED ATTRIBUTABLE RISK OF THYROID CANCER (BOTH SEXES) AS A FUNCTION OF AGE AT EXPOSURE
Attributable risk = radiation-induced cases
radiation-induced cases + spontaneous casesх 100 %
CONCLUSION
Data on Chernobyl are useful for estimating long-term radiological effects following the accident at the Fukushima-1 NPP.
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.