pollution de l’air provenant de véhicules

Pollution de l’air provenant de véhicules

et cancer de la prostate à Montréal, Canada

Colloque de l’IRSPUM, octobre 2013 Marie-Élise Parent, PhD

Collaborateurs

Mark S Goldberg ̶ Dept. of Medicine, McGill University, Montréal

Dan L Crouse ̶ Statistics Canada, Ottawa

Nancy A Ross ̶ Dept. of Geography, McGill University

Hong Chen ̶ Public Health Ontario,Toronto

Alexandre Liautaud ̶ School of Population and Public Health, University of British Columbia

Prostate cancer (PCa)

• Most frequent cancer among men

• Etiology poorly understood

• Established risk factors: age, family history of PCa,

ancestry / geography

• Evidence from migrant studies suggests that risk is

influenced by the environment

Role for the environment?

Prostate is under hormone regulation. Could

environmental factors modulating androgens & estrogens

play an etiological role? Still not substantiated

A few studies have reported associations between

traffic-related air pollution and cancer risk

• Breast cancer (2010, Montréal)

• Cervical cancer (2012, Denmark)

• Brain cancer (2012, Denmark)

• Childhood cancers (2013, California)

• Lung cancer (2013, Europe)

Prostate cancer

• Positive associations in ecological mortality

studies (1960s, New York and Tennessee)

• No association (2012, Denmark)

Traffic-related air pollution

• Local vehicular traffic is the primary contributor to air

pollution in urban areas

• Vehicular emissions include gases, particles, volatile

organic compounds, some of which are potential

carcinogens

• Polycyclic aromatic hydrocarbons and

benzo(a)pyrene have hormone-modulating properties

Our question

Is traffic-related air pollution associated with prostate

cancer risk?

A largely unexplored territory…

Parent et al., Occup Environ Med 2013;70:511-8.

PROtEuS:

The Prostate cancer and Environment Study

• Study base: Greater Montreal

• Case-control

• Age less 76 yrs

• 2,000 cases and 2,000 controls

This analysis (restricted to residents of Island of Montreal):

• 803 incident prostate cancers, histologically confirmed

across French Montreal hospitals (2005-2007)

• 969 population controls from French electoral list, age –

matched (± 5 yrs)

• Response rates: 86% and 63% for cases and controls

PROtEuS

Data collection

• Face-to-face interviews

• Questionnaires eliciting

- Socio-demographics (including current address)

- Lifestyle factors

- Detailed work history

• Biological specimens

Characteristics of the 803 cases and 969 controls

Cases Controls

Mean age (yrs) 64 65

Ancestry (%)

French 71 52

African 9 5

Asian 1 3

Other 18 38

Completed ≥ high school (%) 73 78

Mean BMI 27 27

Family history of PCa (%) 20 11

Assessment of exposure to traffic-related

air pollution

NO2 used as marker of traffic-related air pollution

Montreal survey of NO2 levels

• Estimated by measuring 2-week integrated

concentrations of nitrogen dioxide (NO2) using Ogawa

samplers at 129 locations at 3 times in 2005 and 2006

• Based on land use, road, and traffic data, a

regression model was developed to predict

concentrations of NO2 at all points in the city

• Using historical data from fixed-site monitors, the land

use regression model was extrapolated backward to

1996 and 1985

Crouse D et al., Atmospheric Environment, 2009


• NO2 levels estimated by measuring 2-week integrated








1996 and 1985

Pictures (1)

Anjou, Boul. Metropolitain Park-Extension

ISEE August 2009 15










1996 and 1985

Selected

predictor

variables

• Distance from nearest highway

• Traffic count on nearest

highway

• Length of major roads within

100m

• Area of industrial space within

500m

• Population density within

1000m

Model R2 = .80

Land use regression

model to predict annual

concentrations of NO2 at

a resolution of

5 m X 5 m

ISEE August 2009 18

Park Mont Royal

Downtown

Land Use Regression Map Averaged over three Seasons










1996 and 1985

Distribution of estimates of exposure to

NO2 (ppb)

Minimum Mean Maximum

2006 4.3 11.3 37.4

1996 5.9 15.7 44.5

1985 7.9 20.1 66.8

Hong Chen et al., Atmos Environ 2010

Assigning NO2 exposures to our case-

control series of prostate cancer

1st step: geocoded current addresses

- GeoPinpoint V6.4 (DMTI Spatial, Markham, ON)

- ArcGIS 9.3 geographic information system (GIS)

(ESRI, Redlands, CA)

2nd step: linked current addresses to NO2 exposure

estimates

Results

23

OR for prostate cancer per increase of 5ppb of NO2

Age adjusted Fully adjusted*

Years of estimate of

exposure OR 95%CI OR 95%CI

2005-2006 1.47 1.24-1.75 1.44 1.21-1.73

1996 1.45 1.28-1.65 1.41 1.24-1.62

*Age, ancestry, education, family history of prostate cancer

OR for prostate cancer per increase

of 5ppb of NO2

excluding controls not screened for PC

Fully adjusted*

Years of estimate of

exposure OR 95%CI

2005-2006 1.43 1.18-1.72

1996 1.41 1.22-1.62

*Age, ancestry, education, family history of prostate cancer

Conclusion

NO2, used as a marker of traffic related air pollution,

was associated with prostate cancer risk

Discussion

• Surprising…

• Findings due to chance?

• Confounding? All known risk factors already

accounted for in model

• Bias?

Next step:

Expand NO2 levels to lifetime addresses

The future

• Air pollution and cancer research – still embryonic

• Spatially-referenced data may be particularly useful

for studying the etiology of cancers showing

geographic variations

• Need to further develop (and use!) spatially-

referenced databases

• Associations observed with geographic patterns

can help generate new hypotheses

pollution de l’air provenant de véhicules

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