Molecular Epidemiology Studies of Indoor Air Pollution and Lung Cancer Qing Lan, M.D., Ph.D. Occupational Environmental Epidemiology Branch Division of

Molecular Epidemiology Studies of Indoor Air Pollution and Lung Cancer

Qing Lan, M.D., Ph.D.

Occupational Environmental Epidemiology BranchDivision of Cancer Epidemiology and Genetics

National Cancer Institute

Background: Indoor Air Pollution to Solid Fuels

Half of the world’s population is exposed to smoke from cooking or heating with solid fuels

Indoor air pollution from solid fuel use the eighth largest risk factor for global disease

Coal is used extensively in China for cooking and heating, and is being increasingly utilized to generate electricity in many countries, including the United States

Xinjiang

Xizang

Neimenggu

Qinghai

Sichuan

Gansu

Yunnan

Jilin

Heilongjiang

Hunan

Hebei

Hubei

Guangxi

ShaanxiHenan

Anhui

Jiangxi

Shanxi

Guizhou Fujian

Liaoning

Shandong

Guangdong

Jiangsu

Zhejiang

Ningxi

Taiwan

Hainan

BeijingTianjin

Shanghai

Hongkong

Lung cancer: 1/100,0000 - 55 - 1010 - 1515 - 2020 - No Data

Xuanwei County

County-specific female lung cancer mortality rates (per 100,000, 1973-75)

Lung Cancer Mortality Rates in Xuanwei are among the Highest in China

Xuan Wei County

Xuanwei

Xuan Wei - rural county Semi-mountainous region of Yuan Nan Province >90% of the population are farmers Very stable population < 0.1% of females smoke > 70% of males smoke

Firepit Used in Xuanwei

Average Age of Lung Cancer Patients at Death

Male Female

China 60 60

Shanghai 61 62

Xuan Wei 54 54

He et al., 1987

Annual Lung Cancer Mortality in the 1970s (1/100,000) (age Adjusted to 1964 Chinese Population) among Chinese

Population, Xuanwei County, and Central Xuanwei (1973-79)

6.8

27.7

118

3.2

25.3

125.6

0

20

40

60

80

100

120

140

China Xuanwei Central Xuanwei (use LaiBin coal)

Males

Females

Unique Opportunity for Investigating Lung Cancer and Indoor Air Pollution

Wide range of lung cancer mortality rates cross Xuanwei communes

Very stable population with life-time exposure to smoky coal

Indoor Air Pollution to Solid fuels, Genetic Susceptibility, and Lung Cancer in Xuanwei,

China

Initial work

A. Smoky coal and lung cancer (cohort study)B. Coal type and lung cancer (case-control study)C. Molecular epidemiology and lung cancer (case-control

study)

Ongoing/future work

A. Smoky Coal and Lung Cancer Association

Some homes replaced fire pits with stoves with chimneys reduced exposure to coal combustion

Reduced exposure to coal combustion reduced risk of lung cancer and chronic obstructive pulmonary disease (COPD)?

Retrospective Cohort Study

Goal: To test whether the incidence rates of lung cancer and COPD decreased in subjects who changed from a firepit to a stove with chimney among subjects used Lai Bin coal

Birth period Follow-up period

1917 1951 1976 1992

43,000 subjects

600,000 person-years

1,900 lung cancer cases

2,700 COPD cases

| || |

Stratified Cox Model Risk Ratios for Lung Cancer Incidence Rate, by Sex, in Xuanwei, 1976-1992

Stove improvement

MalesRR (95% CI)

PValue

FemalesRR (95% CI)

P Value

No stove improvement

1.00 --- 1.00 ---

Changed to stove with chimney

0.59 (0.49-0.71) <.001 0.54 (0.44-0.65) <.001

Lan et al., 2002 J Natl Cancer Inst.

Stove Improvement and Lung Cancer in Xuanwei, ChinaProduct-limit survival plot – Probability of not having lung cancer

Males

Females

SC: with chimney

NSI: without chimney


P < 0.001

P < 0.001

Chapman et al., 2005 BMJ

Stove Improvement and COPD in Xuanwei, China Product-limit survival plot – Probability of not having COPD

Females

MalesSC: with chimney

NS: without chimney

P < 0.001

P < 0.001

Indoor Airborne Concentrations of PM10 and BaP in Study Area Homes, by Stove Type, Xuanwei


PM10 BaP

2080 ug/m3

710 ug/m3 250

ng/m3

1660 ng/m3

BaP

Conclusion

Provided strong evidence of a causal association between smoky coal exposure and lung cancer and COPD risk

First evidence on the health benefits of stove improvement in households using coal or biomass fuel

B. Coal Types and Lung Cancer

The cohort study evaluated lung cancer risk from only one type coal, Lai Bin coal

Many other coal types are used as well

Association with lung cancer with other coal types not quantified

B. Coal Types and Lung Cancer

Goal: to examine the relationship between coal type and lung cancer risk

Population-based study, carried out 1985-1990 498 incident cases, 498 individually-matched on age, sex to

controls Participation rates > 95% for both cases and controls Biologic samples were not collected

Odds Ratios (OR) of Lung Cancer in Relation to Coal Type

0.01

0.1

1

10

100

1000

Lai Bin Long Tan LongChang

YangChang

Bao Shan Wen Xing TangTang

Yang Liu Tian Ba Shuan HeOd

ds

Ra

tio

Lan et al., Submitted

P heterogeneity = 5.2x10-10 27.1

4.8

1.3

Coal types

Odds Ratios (OR) of Lung Cancer in Relation to Coal Type, Stratified by Sex

Lan et al., Submitted

Coal types

0.1

1

10

100

Od

ds R

ati

o

Male

Female

Coal types

2.0 (0.9-4.6)3775>120 kg

1.1 (0.5-2.4)3736<=120 kg

1.0 (0.4-2.4)3621<=42.5 kg

13426Never smokers

Cigarette

OR (95% CI)ControlsCases

Tobacco and Lung Cancer Risk in Xuanwei in Men

Adjusted for age, literacy, lung cancer in first-degree relatives, hours spent at home per day, lung disease history, coal mine work history, smoking, and coal type at birth

Conclusion

First etiologic study to report an example where lung cancer risk varies markedly by coal type

. Limited data show that PAH levels vary in

emissions from these coals as well

Evidence indicating PAHs are the key agents in the pathogenesis of lung cancer in this population

Substantial genetic variation in genes that activate and detoxify PAHs and repair DNA damage

Xuanwei provides a unique model of PAH exposure and lung cancer where tobacco does not play a large role

C. Molecular Epidemiology Case-Control Study-- A Pilot Study

Population-based case-control study, carried out in 1995-96

122 incident lung cancer cases and 122 controls individually matched on age and sex

Participation rates > 95% in cases and controls

Collected buccal cell and sputum samples

First epidemiologic study collected biologic samples in this region

Molecular Epidemiology Case-Control Study-- A Pilot Study

Benzo(a)pyrene

B(a)P epoxide

B(a)P diol

B(a)P diolepoxide

CYP1A1, 1A2, 1B1, 3A4, 2C

mEH

CYP1A1, 1A2,1B1; MPO

GSTM1

GSTM1

Detoxification

Detoxification

DNA Adduct, repaired by NER pathway

Catechol

Quinones

AKR1C3 O2

ROSNQO1

UGT1A6

S-Q

UGT2B7

Detoxification

Causes oxidative damage, repaired byBER,DSB pathways

Detoxification

OGG1

Key Pathways in B(a)P Metabolism

GSTM1 null Genotype

GSTM1 null genotype lack of GSTM1 enzyme activity

Results in decreased detoxification of PAH metabolites

a ORs and 95% CIs adjusted for total smoky coal use without ventilation, pack -years, COPD, and family history of lung cancer by multiple conditional logistic regression.

GSTM1 Genotype and Lung Cancer Risk

GSTM1 CaseN (%)

Control N (%)

ORa

(95%CI)

Positive 40(32.8) 62(49.2) 1.0

Null 82(67.2) 60(50.8) 2.3 (1.3-4.2)

Lan et al., 2000 CEBP

GSTM1 Genotype and Lung Cancer Risk, Stratified by Sex

GSTM1 Genotype

CaseN (%)

Control N (%)

OR (95%CI)

Males

Positive 27 (34.18) 38 (48.10)

Null 52 (65.82) 41 (51.90) 1.8 (0.9-3.5)

Females

Positive 13 (30.23) 24 (55.81)

Null 30 (69.77) 19 (44.19) 3.3 (1.3-8.4)

Lan et al., 2000 CEBP

Smoky coal use (tons)

GSTM1Positive Null

<130 1.0 (ref) 1.8 (0.8-4.1)

130 1.8 (0.7-4.6) 5.2 (2.1-12.6)

Interaction between GSTM1 Genotype and Smoky Coal Use and Lung Cancer Risk

Interaction between GSTM1 Null Genotype and Smoky Coal Exposure

GSTM1-positive subjects: the risk of lung cancer increased by 1.2-fold per 100 tons life-time use

GSTM1-null genotype subjects: risk of lung cancer increased by 2.4-fold per 100 tons

(test for multiplicative interaction, P = 0.05)

Benzo(a)pyrene

B(a)P epoxide

B(a)P diol

B(a)P diolepoxide

CYP1A1, 1A2, 1B1, 3A4, 2C

mEH


Detoxification

Detoxification


Catechol

Quinones

AKR1C3O2

ROSNQO1

UGT1A6

S-Q

UGT2B7

Detoxification


Detoxification


Aldo-keto Reductase Family 1, Member C3 (AKR1C3 Gln5His)

AKR1C3-Gln5His polymorphism (Exon 1) Produces a change from glutamine histidine A shift from a neutral to a basic amino acid

AKR1C3-Gln5His Polymorphism and Lung Cancer Risk

Lan et al., 2004 Carcinogenesis

Genotype Case Controls OR (95%CI)

N (%) N (%)

His/His + His/Gln 22 (19) 33 (29) 1.0

Gln/Gln 94 (81) 79 (71) 1.8 (1.0-3.5)

AKR1C3 Genotype and Lung Cancer Risk, Stratified by Sex and Smoky Coal Use

ORs and 95%CIs obtained by logistic regression analysis adjusted for age, sex, pack-year of smoking.

0.9 (0.2-5.0)1.5 (0.5-4.4)

1.01.0

MalesHis/His+His/Gln

Gln/Gln

13.2 (2.3-109.2)1.00 (0.2-5.8)Gln/Gln

1.01.0His/His+His/Gln

Females

>=130 tons<130 tonsGenotype

Smoky Coal Use (tons) OR (95% CI)


Benzo(a)pyrene

B(a)P epoxide

B(a)P diol

B(a)P diolepoxide

CYP1A1, 1A2, 1B1, 3A4, 2C

mEH


Detoxification

Detoxification


Catechol

Quinones

O2

ROSNQO1

UGT1A6

S-Q

UGT2B7

Detoxification


Detoxification

OGG1


OGG1 (Oxoguanine glycosylase 1) Ser326Cyspolymorphism

• OGG1 repairs 8-oxo-7,8-dihydroguanine (8oxoG)

• OGG1 Ser326Cys polymorphism (Exon 6)

• Repair activity of OGG1-Ser326 has been shown to be > OGG1-Cys326

OGG1 Ser326Cys Polymorphism and Lung Cancer Risk



OGG1 Genotype

CaseN (%)

Control N (%)

OR (95%CI)

Ser/Ser 37 (31) 51 (47) 1.0

Ser/Cys+Cys/Cys

81 (69) 58 (53) 1.9 (1.1-3.3)

OGG1 Genotype and Lung Cancer Risk, Stratified by Sex and Smoky Coal Use


2.0 (0.7-5.6)1.2 (0.5-2.9)

1.01.0

MalesSer/Ser

Gln/Gln +Cys/Cys

5.8 (1.1-34.8)1.3 (0.3-5.3)Gln/Gln +Cys/Cys

1.01.0Ser/Ser

Females

>=130 <130 Genotype

Smoky Coal Use (tons) OR (95% CI)


Limitations

Small sample size can lead to false positive findings

Critical to replicate and extend findings

GSTM1 Genotype and Lung Cancer in Asian Populations with Indoor Air Pollution Exposure to Coal Combustion

Products: a Meta-Analysis

Odds ratio.2 1 5

Study % Weight Odds ratio (95% CI)

2.12 (1.26,3.56) Lan, 2000 22.9

1.97 (1.20,3.23) Chen, 2006 24.7

1.58 (0.93,2.66) Wang, 2003 22.6

1.18 (0.76,1.84) Yang, 2004 29.8

1.64 (1.25,2.14) Overall (95% CI)

Hosgood et al., 2007 Mutat Res.

1.64 (1.25-2.14)560 cases and 635 controls

Study –

Lan, 2000

Chen, 2006

Wang, 2003

Yang, 2004

Overall (95% CI)

Recent Meta-analysis of the GSTM1 Null Genotype and Lung Cancer in General Population

General population 130 studies, 23,452 lung cancer cases and 30,397 controls: OR = 1.18 (95% CI: 1.14–1.23)

Sample size > 500: OR = 1.04 (95% CI: 0.95–1.14) Asian Populations with Indoor Air Pollution Exposure to

Coal Combustion Products: OR = 1.64 (1.25–2.14)

GSTM1 null genotype may influence risk of lung cancer in populations exposed to high levels of indoor combustion products containing PAHs.

Conclusions of Initial Xuanwei Lung Cancer Studies

Smoky coal with high levels of PAH is the main cause of lung cancer

Variants in genes involved in activation and detoxification of PAH may modify the smoky coal-lung cancer association, particularly in women

Impact of Research Findings

IARC monograph, “Carcinogenicity of household use of solid fuels and high temperature frying ” classified indoor emissions from household combustion of coal as “carcinogenic to humans - Group 1”

(October 16, 2006)

Unanswered Questions

What is the dose-response relationship between PAH exposure and lung cancer risk?

What is the role of genetic susceptibility for lung cancer risk overall and as a modifier of the PAH association?

What are the unique characteristics of tumors in this population?

Initiation of a New Case-Control of Lung Cancer among Nonsmoking Women in Xuan Wei (2006-2008)

Enroll 750 non-smoking female cases and 750 female controls

Biological sample collection: collect blood, sputum, buccal cells, and tumor tissue

Questionnaire collects extensive information on lifetime exposure to smoky coal, potential confounders

Detailed exposure assessment including personal and stationary air monitoring

Yunnan Province

Advantages of the New Study Enhanced diagnostic accuracy (special cytologic methods)

Increased sample size with adequate power to detect magnitude of effects observed previously

Extensive collection and processing of biologic samples

Will provide new mechanistic insights into the pathogenesis of lung cancer

Will provide important quantitative risk estimates from coal combustion and PAH exposure (US EPA)

About 300 cases and 300 controls have been enrolled to date

Subject enrollment will be completed in 18 months

Participation rates have been > 90% for both cases and controls

Accomplishments to Date of New Lung Cancer Study

Future Directions Genetic analysis in case-control study of nonsmoking women in

XW Tag SNP and functional variants in candidate genes important for PAH Also include SNPs in genes identified from ongoing genome-wide association studies of lung cancer Analyze main effects and interaction with PAH exposure

Detailed exposure assessment

International Lung Cancer Consortium (ILCCO) Co-chair of working group on non-smoking lung cancer Planning pooled analyses to study risk factors for lung cancer in various non-

smoking populations

CollaboratorsChina EPA: Fusheng Wei

China CDC: Xingzhou He

U.S. EPA: Robert Chapman, Judy Mumford

University of Utrecht: Roel Vermeulen

IARC: Pierre Hainaut

UC Berkeley: Kathy Hammond

University of Utah: Richard Cawthon

Chinese University of Hong Kong: Linwei Tian

U.S. NCI: Min Shen, Roel Vermeulen, Nat Rothman, Neil Caporaso, Aaron Blair, Jay Lubin, Michael Alavanja, Stephen Chanock

1

4

7

10

13

16

19

22

25

28

0 50 100 150

BaP (ug/100 m3)

Od

ds

Rat

ios

r = 0.93, p = 0.0025

Correlation between BaP Exposures from a Specific Coal Types and Lung Cancer Risk

Documents

Molecular Epidemiology Studies of Indoor Air Pollution and Lung Cancer Qing Lan, M.D., Ph.D. Occupational Environmental Epidemiology Branch Division of