VK Ivanov Chairman Russian Scientific Commission on Radiological Protection Medical Radiological Research Center National Radiation and Epidemiological Registry The International Workshop on ID: 814486
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Slide1
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
Slide2
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-induced
thyroid
cancer
incidence
+
Estimating
SCREENING EFFECT
EstimatingRADIATION RISK
Why… & How estimate…?
Slide3Slide4NRER 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
i
n Radiation Epidemiology
23
regional centers
4 000
hospitals
and clinics
798 000
registered persons
400 000
Individual doses
18
000 000
diagnoses
NATIONAL RADIATION
AND
EPIDEMIOLOGICAL REGISTRY
STRUCTURE OF THE REGISTERED PERSONS
Slide5COHORT SELECTED FOR ANALYSIS OF RADIATION RISK OF THYROID CANCER
Size of Cohort: 309,
130 individuals with known thyroid dose (people living in contaminated
areas
137
Cs ≥ 5
Ci
/km
2
) Bryansk
, Kaluga, Orel and Tula regions
1980
1986
1991
2008
r
egistration
o
f persons
Start of follow-up
End of follow-up
18 years
Follow-up period:
Age at exposure (1986), y
Registered
persons
Observed
cases
N
%
N
0-17
97,191
31 %
24718 +211,93969 %746Total309,130100 %993Cases: 993 Thyroid cancers (ICD-10: C73)
Slide6AVERAGE
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.
Slide7METHODS:
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
Slide8METHODS:
Baseline thyroid cancer incidence rate
0rus – thyroid cancer incidence rate in RussiaSIR –
standardized incidence ratio
(
SCREENING EFFECT
)
Slide9METHODS:
Assessment of screening and dose response
Thyroid dose,
Gy
SCREENING EFFECT
ERR (dose response)
Slide10Follow-up: 1991 – 2008
Age 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)
Slide11Follow-up: 1991 – 2008
Age 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-value
10.55 (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)
Slide12RELATIVE 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
0.2221897,5001.64 (0.93; 2.76)0.0850.25-0.30.2731675,4202.15 (1.18; 3.69)0.0130.3-0.350.3241744,4323.12 (1.75; 5.30)< 0.0010.35-0.50.4182094,7912.31 (1.35; 3.83)0.003> 0.50.86019107,5042.40 (1.36; 4.03)0.002Model of Relative Risk:
Slide13RELATIVE 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)
Slide14EXPANDED 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
r
egistration
o
f persons
Start of follow-up
End of follow-up
21 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)
Slide15INCIDENCE RATE OF THYROID
CANCER IN MALE POPULATION OF THE RUSSIAN FEDERATION
Slide16INCIDENCE RATE OF THYROID CANCER
IN FEMALE POPULATION OF RUSSIAN FEDERATIONsex-ratio incidence:
Slide17OBSERVED AND EXPECTED NUMBER OF
THYROID CANCER CASES AMONG CHILDREN AND ADOLESCENTS (0-17 y. in
1986)BY CALENDAR PERIODS
Slide18SIR OF THYROID CANCER AMONG CHILDREN AND
ADOLESCENTS AS A FUNCTION OF CALENDAR PERIOD IMPORTANT!
SIR includes the radiation risk => SIR ≠ SCREENING
Slide19Follow-up: 1991 – 2011
0-17 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
Slide20Follow-up: 1991 – 2011
0-17 y at the time of the Chernobyl accident
SCREENING EFFECT by periods, 95% CI
1991 –
1995
15.2 (10.6; 20.9)
199
6
–
2000
7.5 (5.5; 9.9)
200
1 –
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
Slide21NEW 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)
Slide22Dose range,
mGy
Average thyroid dose, mGy
Cases
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 – 300 110.42184.05 (1.09; 9.16)0.003 0 – 500 139.62535.15 (2.39; 9.73)< 0.001 0 – 1000172.32694.31 (2.16; 7.75)< 0.001 > 0189.42723.81 (1.81; 6.86)< 0.001THYROID 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
Slide23FITTED ATTRIBUTABLE RISK OF THYROID CANCER (BOTH SEXES) AS A FUNCTION OF AGE AT EXPOSURE
Attributable risk =
radiation-induced casesradiation-induced cases +
spontaneous cases
х
100
%
Slide24CONCLUSION
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.
Slide25Thank you for your attention