Environment and Breast Cancer: Science Review

Evidence From Humans
Print this page
NO(2) and cancer incidence in Saudi Arabia
Al-Ahmadi, K., Al-Zahrani, A. Int J Environ Res Public Health. 2013. 10:11, 5844-62.
Topic area
Environmental pollutant - Air pollution NO2
Study design
Study Participants
Menopausal Status
The menopausal status of women included in this study is listed here.
No analysis based on menopausal status
Participant selection: Inclusion and exclusion criteria
Criteria used to select participants in the study.
Breast cancer cases identified from the Saudi Arabian Cancer Registries, diagnosed between 1998-2004 in the country's 13 regions. Number of cases not stated.
Comment about participation selection
National reporting data does not include information that may alter breast cancer risk, such as hormone replacement therapy use or family history.
Exposure Investigated
Exposures investigated
2003-2010 NO2 data from global satellite monitoring used as a proxy for fossil fuel and biofuel combustion, power plants, industry, and vehicular traffic.
How exposure was measured
Environmental sample GIS/geographic location
Exposure assessment comment
Geographically weighted regression allows relationships between variables to vary spatially.
Breast cancer outcome investigated
Primary incident breast cancer
Confounders considered
Other breast cancer risk factors, such as family history, age at first birth, and hormone replacement therapy use, that were taken into account in the study.
None are specifically listed. However, authors state the GWR model "is adjusted based on the data that are geographically close to a specific location."
Genetic characterization included
If the study analyzed relationships between environmental factors and inherited genetic variations, this field will be marked “Yes.” “No”, if not.
Strength of associations reported
Regional level NO2 (ordinary least square regression) explained 71% of the variation in the crude incidence rate (CIR) (p<0.05).

Governorate level NO2 (geographically weighted regression) explained 39% of the variation in the CIR (p<0.05).

City level NO2 (geographically weighted regression) explained 11% of the variation in the CIR (p<0.05).
Results Comments
Authors note that results may be significant at regional level, but not governorate or city level because the regional level may capture more variation in NO2 between urban and rural areas. NO2 data reflect levels between 2003-2010, after the breast cancer cases were registered.
Author address
King Abdulaziz City for Science and Technology, P.O. Box 6086, Riyadh 11442, Saudi Arabia. alahmadi@kacst.edu.sa.
Reviewers Comments
A limitation of the ecologic study design is the lack of individual risk factor information.