Environment and Breast Cancer: Science Review

Epidemiological evaluation of breast cancer in ecological areas of Kazakhstan--association with pollution emissions
Bilyalova, Z., Igissinov, N., Moore, M., Igissinov, S., Sarsenova, S., Khassenova, Z. Asian Pacific journal of cancer prevention: APJCP. 2012. 13:5, 2341-4.

Topic area
Environmental pollutant - Air pollution, vehicle exhaust
Environmental pollutant - Air pollution, vehicle exhaust
Study design
Ecologic
Ecologic
Funding agency
Not reported
Not reported

Study Participants
Number of Cases
31,197
31,197
Menopausal Status
The menopausal status of women included in this study is listed here.
No analysis based on menopausal status
Number of Controls
Not reported
Not reported
Country where study was conducted
Kazakhstan
Kazakhstan
Participant selection: Inclusion and exclusion criteria
Criteria used to select participants in the study.
Data on first-time breast cancer patients were compiled from the Cancer Registry of the Kazakh Research Institute of Oncology and Radiology for the years 1999 to 2009. Data on the female population were obtained from the Agency of the Republic of Kazakhstan for the same study period.

Exposure Investigated
Exposures investigated
Residence in eight ecologic zones was used as a surrogate for exposure to air pollution emissions. Data on pollution emissions for each region were obtained from the 2007 and 2010 Demography Yearbook of Kazakhstan regions.
Residence in eight ecologic zones was used as a surrogate for exposure to air pollution emissions. Data on pollution emissions for each region were obtained from the 2007 and 2010 Demography Yearbook of Kazakhstan regions.
How exposure was measured
Geographic area
Geographic area
Exposure assessment comment
Analyses did not include a model of individual-level cumulative exposure based on duration of exposure, proximity to emissions sources, specific industrial emissions in each region, or non-residential sources of exposure such as occupation.
Analyses did not include a model of individual-level cumulative exposure based on duration of exposure, proximity to emissions sources, specific industrial emissions in each region, or non-residential sources of exposure such as occupation.
Breast cancer outcome investigated
Primary incident breast cancer
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
Genetic characterization included
If the study analyzed relationships between environmental factors and inherited genetic variations, this field will be marked “Yes.” “No”, if not.
No
Strength of associations reported
Correlation between emissions per capita (kg) and incidence of breast cancer among women aged 30-39 years: r=0.74, p=0.036
Correlation between emissions per capita (kg) and incidence of breast cancer among women aged 40-49 years: 0.69, p=0.058
Correlation between emissions per capita (kg) and incidence of breast cancer among women aged 60-69 years: r=0.83, p=0.011
Correlation between emissions per capita (kg) and incidence of breast cancer among age groups 70 years and older: r=0.71, p=0.049
Correlation between emissions per capita (kg) and incidence of breast cancer among women aged 30-39 years: r=0.74, p=0.036
Correlation between emissions per capita (kg) and incidence of breast cancer among women aged 40-49 years: 0.69, p=0.058
Correlation between emissions per capita (kg) and incidence of breast cancer among women aged 60-69 years: r=0.83, p=0.011
Correlation between emissions per capita (kg) and incidence of breast cancer among age groups 70 years and older: r=0.71, p=0.049
Results Comments
The correlation between emissions per capita and breast cancer incidence among women aged 50-59 years was not reported. The highest incidence rates among this age group were observed in Nura-Sarysu and Irtysh, which also have the highest emissions per capita in comparison to the other ecologic regions.
The correlation between emissions per capita and breast cancer incidence among women aged 50-59 years was not reported. The highest incidence rates among this age group were observed in Nura-Sarysu and Irtysh, which also have the highest emissions per capita in comparison to the other ecologic regions.

Author address
Central Asia Cancer Institute, Astana, Kazakhstan.
Central Asia Cancer Institute, Astana, Kazakhstan.
Reviewers Comments
The lack of individual-level information in an ecologic study design limits interpretations of associations. The authors did not control for socioeconomic status or other demographic variables which may be associated with emissions per capita in each ecologic zone.
The lack of individual-level information in an ecologic study design limits interpretations of associations. The authors did not control for socioeconomic status or other demographic variables which may be associated with emissions per capita in each ecologic zone.