Environment and Breast Cancer: Science Review

Evidence From Humans
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The risk of breast cancer in relation to health habits and occupational exposures
Shaham, J., Gurvich, R., Goral, A., Czerniak, A. Am J Ind Med. 2006. 49:12, 1021-30.
Topic area
Environmental pollutant - Occupation
Study design
Population based case-control
Funding agency
Not reported
Study Participants
Menopausal Status
The menopausal status of women included in this study is listed here.
No analyses based on menopausal status
Number of Controls
Controls: 413
Participant selection: Inclusion and exclusion criteria
Criteria used to select participants in the study.
Cases were women diagnosed with histopathologically confirmed breast cancer between 1980 and 2001, recruited from a regional hospital in Holon, Israel. Controls were selected from the Ministry of the Interior's National Population Registry for the region, and had no prior diagnoses of cancer.
Comment about participation selection
There was no mention of matching factors for cases and controls. Because the recruitment time frame was >20 years, the controls may not be representative of the population from which the cases were ascertained. For example, a good comparison for a participant diagnosed with breast cancer in 1980 would be a woman who was healthy in 1980, not necessarily a woman who was healthy in 2001.
Exposure Investigated
Exposures investigated
Each self-reported job held by a participant was categorized into one of 18 occupational groups. A participant was allocated into an occupational group if she had ever been employed in that field. Participants were also allocated into exposure groups base
How exposure was measured
Job history Questionnaire, by telephone
Exposure assessment comment
All job titles were categorized into occupational groups, but the authors do not discuss excluding any occupations based on length of employment (e.g. <1 year). Proportion of participants ever employed not reported. Self-reported exposure to occupational hazards (i.e. ionizing radiation, organic solvents) may be subject to recall bias.
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.
Age, continent of origin (Asia/Africa, Europe/America, Israel), family history, number of births, diet. Age at menarche, years of ovulation, age at first full-term pregnancy, HRT use, and smoking status were compared between cases and controls but it does
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
Compared to never worked in the job/industry:
Administration: aOR 0.6 (95% CI 0.4-0.9)
Textile, clothing: aOR 1.8 (95% CI 1.1-3.0)
Various industries: aOR 4.3 (95% CI 2.0-9.3)
Exposure to ionizing radiation: aOR 5.3 (2.0-14.1)
Results Comments
The occupational group, "Various Industries," is not defined. Effect estimates were reported for other occupational categories (cleaning, health service, cosmetologists/hairdressers, agriculture, printing) and specific occupational exposures (organic solvents, 'chemicals', cleaning chemicals, hair dyes, paints, textile paints, fibers, etc.) but these were not considered in multivariable models accounting for potential confounders (other than age and origin).
Author address
Occupational Cancer Department, National Institute of Occupational and Environmental Health, Raanana, Israel. yshaham@bezeqint.net
Reviewers Comments
Other occupational studies have reported that women in administrative jobs have an increased risk of breast cancer, as opposed to the protective estimate observed in this study.