Environment and Breast Cancer: Science Review

Evidence From Humans
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An Italian population-based case-control study on the association between farming and cancer: are pesticides a plausible risk factor?
Salerno, C., Carcagni, A., Sacco, S., Palin, L. A., Vanhaecht, K., Panella, M., Guido, D. Arch Environ Occup Health. 2016. 0.
Topic area
Environmental pollutant - Pesticides
Study design
Population based case-control
Funding agency
None reported
Study Participants
Menopausal Status
The menopausal status of women included in this study is listed here.
No analysis based on menopausal status
Number of Controls
Controls: 11,491
Cohort participation rate
Not applicable, this is a records based study
Participant selection: Inclusion and exclusion criteria
Criteria used to select participants in the study.
The underlying population was considered to be all residents ages 25-79 living for at least one year during 2002-2009 in the suburban area of Vercelli. Since there is no cancer registry in this area, cases were considered first hospital admissions for cancer, identified from hospital discharge forms and the Italian National Institute of Statistics death forms and cross-checked with histopathology reports. Controls were residents in the same province at the same time as controls, aged 25-79, with no prevalent cancer.
Comment about participation selection
The number of controls is far greater than the number of cases. Since cases were hospital-based and controls were not, the distribution of health-related risk factors in the two groups may be different.
Exposure Investigated
Exposures investigated
Occupation (farmer) as a proxy for pesticide exposure
How exposure was measured
Job history (from social security records)
Exposure assessment comment
A small number of cases has multiple cancers, and the profession of the subject was only counted once in these instances. The authors note that the exposure measurement is crude and prone to misclassification.
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.
Gender and age were adjusted for in the analysis, while occupational risk factors related to farming were taken as explanatory variables and the municipality of residence was included in the generalized linear mixed models to improve fit.
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
Ever worked as farmer vs. never: OR 1.72 (95% CI 1.04-2.85)
Results Comments
One male breast cancer case was included in the study.
Author address
a Department of Translational Medicine . University of Eastern Piedmont "Amedeo Avogadro" . Via Solaroli n. 17-28100 Novara , Italy .
Reviewers Comments
As the authors note, major risk factors (genetic and socio-demographic information, place of birth, proximity to health-risky sites, tobacco smoking, alcohol consumption) and the large number of control subjects were not taken into consideration in the analysis. Because the general population was chosen as the comparison population, these results may be underestimated due to the healthy worker effect.