Thyroid Disease among A-bomb Survivors Exposed in

Childhood

Roy Shore, Kyoji Furukawa, Misa ImaizumiRadiation Effects Research Foundation

shore@rerf.or.jp

Atomic Bomb Survivor Study Overview

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A-bomb Study Characteristics

Life Span Study Includes >86,000 survivors of all ages at exposure, with

estimated doses and long follow-up for mortality (1950-2008) and cancer incidence (1958-2009)

Includes 13,000 exposed before age 5 and 9,500 at ages 5-9, with a wide range of doses (1 mGy to >3 Gy)

Adult Health Study (clinical examinations) Includes >2,600 under 10 years of age, given ultrasound

screening

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0- 5- 50- 100- 200- 500- 1000- 2000+0

10

20

30

40

50

Thyroid Weighted Absorbed Dose (mGy)

Thyroid dose distribution among those <10 years old at exposure is similar to these.

Pro

po

rtio

n (

%)

37,164

23,107

6,753 6,141 6,545

3,7952,214

952

　　　　 Life Span Study (LSS) Thyroid Dose Distribution

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Thyroid Cancer Risk in theLife Span Study (LSS)

5

Weighted absorbed thyroid dose (Gy)

(Modeled for age 10 at exposure and age 60 at risk)

(Furukawa et al, Int J Cancer, 132:1222-26, 2013)

Exc

ess

Rel

ativ

e R

isk

(ER

R)

weighted thyroid dose (Gy)

exce

ss r

ela

tive

ris

k

0

1

2

3

4

0.0 0.5 1.0 1.5 2.0 2.5

4

3

2

1

0

0.0 0.5 1.0 1.5 2.0 2.5

ERR Gy-1 = 1.28 (95%CI 0.6, 2.7)

LSS Thyroid Cancer: Dose-response

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Study ERR (95% CI) per Gy

EAR (95% CI) per 104 PY Gy

LSS (Furukawa 2013) (est. for IR at age 10) 1.3 (0.6, 2.7) 3.0 (1.4, 5.0)

Rochester thymus x-ray (age 0; Adams 2010) 3.2 (1.5, 6.6) 2.2 (1.4, 3.2)

Israel tinea capitis x-ray (ages 0-15; Sadetzki 2006) 20.2 (12, 32) 9.9 (5.7, 15)

Michael Reese tonsils x-ray (ages 0-15; Ron 1995) 2.5 (0.6, 26) 3.0 (0.5, 17)

Childhood cancer RT (pooled; Veiga 2012) 1.3 (0.7, 2.3) N.A.

Comparison of LSS Thyroid Cancer Risk with Other Studies of Childhood External Radiation

Exposure

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Comparison of LSS Thyroid Cancer Risk with Chernobyl Studies of 131I

Exposure

Study ERR (95% CI) per Gy

EAR (95% CI) per 104 PY Gy

LSS (Furukawa 2013) (est. for IR at age 10) 1.3 (0.6, 2.7) 3.0 (1.4, 5.0)

Ukraine (screening, exposure ages 0-17; Brenner 2011)

1.9 (0.4, 6.3) 2.2 (0.04, 5.8)

Belarus (screening, exposure ages 0-18; Zablotska 2011)

2.2 (0.8, 5.5) N.A.

Ukraine & Belarus (Ecological, ages 0-18; Jacob 2006)

18.9 (11, 27) 2.7 (2.2, 3.1)

8

20 30 40 50 60 70 80 90

02

46

81

0

attained age

Exc

ess

re

lativ

e r

isk

at 1

Gy

age at exposure

-55-910-1920-2930-

ERR

20 30 40 50 60 70 800

20

40

60

80

attained age

Exc

ess

ca

ses

at 1

00

,00

0 P

Y-G

y

EAR

(Adapted from: Furukawa et al, Int J Cancer, 132:122-26, 2013)

Thyroid Cancer Risk by Age at Exposure and Attained Age

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Thyroid Disease at Clinical Examination in the Adult

Health Study (AHS)

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Methods for Diagnosis of Thyroid Diseases

Thyroid examination at the routine AHS health examination Questionnaire: previous thyroid diseases and treatments, family

history, seaweed intake

Ultrasound examination (detected nodules 5mm)≧ Aspiration biopsy (solid nodules ≧10mm)

Blood tests

• Thyroid function : FT3, FT4, TSH

• Thyroid antibodies

Tumor information from Tumor Registries Medical information (e.g. results of cytology, pathology) from

hospitals

(Imaizumi et al, 2013, unpublished)

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12

Radiation Dose and Solid Thyroid Nodules, AHS Screening

0

2

4

6

8

10

0 2 41 3

Od

ds

Rat

io

Thyroid weighted absorbed dose, Gy

EOR/Gy= 2.0 (95%CI 1.3, 2.9), n=464 nodules

(Imaizumi et al, JAMA, 295:1011-22, 2006)

0

2

4

6

8

10

0 2 41 30

2

4

6

8

10

0 2 41 3

13

Od

ds

Rat

io

Thyroid weighted absorbed dose, Gy

EOR/Gy= 2.0 (95%CI 0.7, 4.9), n=70 cancers

Od

ds

Rat

ioThyroid weighted absorbed dose, Gy

EOR/Gy= 1.5 (95%CI 0.8, 2.7), n=156 nodules

Radiation Dose, Thyroid Cancers and Benign Thyroid Nodules, AHS Screening

Thyroid Cancers Benign Nodules

(Imaizumi et al, JAMA, 295:1011-22, 2006)

In Utero-exposed Clinical Cohort: Radiation Dose-response for Solid Thyroid Nodules

0 1 2

0

2

4

6

8

10

12

14

16

18

20

Od

ds

Ra

tio

Maternal Uterine Dose (Gy)

Solid NodulesOR at 1 Gy = 2.78

(95% CI: 0.50, 11.8)P = 0.22

(Imaizumi et al, J Clin Endocrinol Metab. 2008;93:1641-8)

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Summary of RERF Radiation and Thyroid Effects

Over the dose range 0-2 Gy, a linear model fits reasonably well.

Linear dose-response risk estimate is comparable to nearly all other studies of external irradiation and Chernobyl thyroid studies

For those with <100 mGy: Increased risk is uncertain, due to little risk and/or limited statistical power.

Those exposed at young ages are clearly at the highest thyroid cancer risk. Little risk is seen for those exposed as adults.

Thyroid cancer risk continues for >50 years after exposure.

Risk of benign solid thyroid nodules is increased by radiation

Probably a dose-related risk of thyroid nodules after in utero exposure, though this study lacked statistical power to fully determine

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