Evidence From Humans
 
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Postmenopausal breast cancer and occupational exposures
Labreche, F., Goldberg, M. S., Valois, M. F., Nadon, L. Occup Environ Med. 2010. 67:4, 263-9.
Topic area
Environmental pollutant - Occupation Organic Solvents PAHs
Study design
Hospital based case-control
Funding agency
Canadian Breast Cancer Research Alliance (c/o Cana
Study Participants
Menopausal Status
The menopausal status of women included in this study is listed here.
Analyses restricted to postmenopausal status
Number of Controls
Controls: 613
Participant selection: Inclusion and exclusion criteria
Criteria used to select participants in the study.
Cases were postmenopausal women diagnosed with primary, malignant breast cancer in 1996 and 1997, between the ages of 50 and 75, while living in the greater Montreal area. Hospital-based controls were newly diagnosed cancer cases (32 different sites), selected from the same hospital and time period as the cases, and frequency matched by age. Controls with diagnoses for certain cancer sites were excluded due to possible associations of those cancers with occupational exposures. Non-melanoma skin cancer was excluded because it is diagnosed mostly out of hospital.
Comment about participation selection
Authors report that case ascertainment was complete, as subjects were identified from hospital records and cancer registries. Use of cancer controls may have reduced potential recall biases. Although cancers known to be associated with occupation were excluded from the controls, some included cancers, such as endometrial and ovarian, could have occupational risk factors, perhaps the same as for breast cancer.
Exposure Investigated
Exposures investigated
A team of experienced industrial hygienists and chemists reviewed general and job-specific questionnaires and developed exposure indices for about 300 chemical and physical agents. The reviewers were blinded to the case/control status of the participants.
How exposure was measured
Questionnaire, by telephone Questionnaire, in person Job history
Exposure assessment comment
Proxy respondents (usually spouses) employed for 13% of controls and 5% of cases. There were few exposed participants, especially considering exposure before age 36 and tumor sub-type. The Healthy Worker Effect may be a concern because the comparison group included non-workers.
Early life exposures considered
Yes, accounting for exposure before age 36
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, family history, age at oophorectomy, education, ethnicity, age at menarche, oral contraceptive use, duration of HRT, total duration of breastfeeding, smoking status, BMI, and proxy respondent status
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
Volatile organic liquids:
Ever vs. never: OR 0.98 (95% CI 0.74-1.31)
Ever substantial exposure vs. never: OR 0.82 (95% CI 0.48-1.40)
Ever substantial exposure vs. never, 10-year lag: OR 0.83 (95% CI 0.48-1.43)
Substantial exposure < age 36 vs. never: OR 0.91 (95% CI 0.47-1.75)

Organic solvents with reactive metabolites:
Ever vs. never: OR 1.09 (95% CI 0.67-1.77)
Ever substantial exposure vs. never, 10-year lag: OR 0.80 (95% CI 0.32-2.01)
Substantial exposure < age 36 vs. never: OR 1.11 (95% CI 0.38-3.24)
Lifetime exposures, per 10-year increase: OR 1.14 (95% CI 0.80-1.62)
Exposures < age 36, per 10-year increase: OR 1.30 (95% CI 0.65-2.60)
ER+/PR+, lifetime exposures, per 10 year increase: OR 1.27 (95% CI 0.56-2.90)

Acrylic fibers:
Lifetime exposures, per 10-year increase: OR 1.93 (95% CI 1.16-3.23)
Exposures < age 36, per 10-year increase: OR 7.69 (95% CI 1.47-40.24)
ER+/PR+, lifetime exposures, per 10-year increase: OR 2.44 (1.15-5.18)

Aliphatic aldehydes:
Lifetime exposures, per 10-year increase: OR 1.00 (95% CI 0.84-1.18)
Exposures < age 36, per 10-year increase: OR 1.25 (95% CI 0.87-1.80)

Carbon monoxide:
Lifetime exposures, per 10-year increase: OR 0.98 (95% CI 0.79-1.23)
Exposures < age 36, per 10-year increase: OR 1.66 (1.20-2.70)
ER+/PR- subtype, exposures < age 36, per 10-year increase: OR 2.58 (95% CI 0.96-6.94)

Inks:
Lifetime exposures, per 10-year increase: OR 1.50 (95% CI 0.92-2.45)
Exposures < age 36, per 10-year increase: OR 2.89 (95% CI 0.96-8.71)

MAHs:
Lifetime exposures, per 10-year increase: aOR 1.27 (95% CI 0.83-1.93)
Exposures < age 36, per 10-year increase: OR 1.62 (95% CI 0.67-3.92)
ER+/PR-, lifetime exposures, per 10-year increase: OR 3.24 (95% CI 1.23-8.53)

Nylon fibers:
Lifetime exposures, per 10-year increase: OR 1.14 (95% CI 0.87-1.50)
Exposures < age 36, per 10-year increase: OR 1.99 (95% CI 1.02-3.88)
ER+/PR+, exposures < age 36, per 10-year increase: OR 2.00 (95% CI 0.95-4.21)

PAHs from any source:
Lifetime exposures, per 10-year increase: OR 1.21 (95% CI 0.90-1.61)
Exposures < age 36, per 10-year increase: OR 1.75 (95% CI 0.99 to 3.10)

PAHs from petroleum:
Lifetime exposures, per 10-year increase: OR 1.52 (95% CI 0.97-2.39)
Exposure < age 36, per 10-year increase: OR 2.38 (95% CI 1.00-5.67)
ER+/PR+, lifetime exposures, per 10-year increase: OR 1.65 (95% CI 0.97-2.83)
ER+/PR+, exposures < age 36, per 10-year increase: OR 3.00 (95% CI 1.10-8.13)

Polyester fibers:
Lifetime exposures, per 10-year increase: OR 1.03 (95% CI 0.80-1.32)
Exposures < age 36, per 10-year increase: OR 1.62 (95% CI 0.87-2.99)

Rayon fibers:
Lifetime exposures, per 10-year increase: OR 1.51 (95% CI 1.00-2.28)
Exposures < age 36, per 10-year increase: OR 2.65 (95% CI 0.91-7.73)
ER+/PR-, lifetime exposures, per 10-year increase: OR 2.40 (95% CI 1.24-4.65)

Synthetic fibers:
Lifetime exposures, per 10-year increase: OR 1.07 (95% CI 0.87-1.31)
Exposures < age 36, per 10-year increase: OR 1.53 (95% CI 0.95-2.46)
ER+/PR+, lifetime exposures, per 10-year increase: OR 1.70 (95% CI 0.97-2.95)

Wool fibers:
Lifetime exposures, per 10-year increase: OR 1.24 (95% CI 0.96-1.60)
Exposures < age 36, per 10-year increase: OR 1.73 (95% CI 1.01-2.97)
Results Comments
Non-significant elevated OR for substantial exposures before age 36. Higher odds of ER+/PR- and ER+/PR+ tumors among women exposed before age 36.
Author address
Institut de recherche Robert-Sauve en sante et en securite du travail du Quebec, 505 boul. de Maisonneuve Ouest, Montreal, Quebec, Canada H3A 3C2. france.labreche@irsst.qc.ca
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