Environment and Breast Cancer: Science Review

Evidence From Humans
Print this page
Female breast cancer in Lombardy, Italy (2002-2009): a case-control study on occupational risks
Oddone, E., Edefonti, V., Scaburri, A., Vai, T., Crosignani, P., Imbriani, M. Am J Ind Med. 2013. 56:9, 1051-62.
Topic area
Environmental pollutant - Occupation
Study design
Other: registry-based case-control
Funding agency
San Paolo Foundation University of Turin
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: 25,329
Cohort participation rate
Not applicable. This study was records-based.
Participant selection: Inclusion and exclusion criteria
Criteria used to select participants in the study.
44,486 women residing in Lombardy, Italy and diagnosed with breast cancer 2002-2009 between the ages 35-69 were identified through hospital discharge records as part of the Occupational Cancer Monitoring (OCCAM) project. Women diagnosed during the period 1999-2001 were excluded. 53,095 controls were randomly sampled, with matching to cases by province of residence and 5-year age groups, from the regional list of citizens registered with the National Health Service as of December 31, 2015. "Blue collar" workers were then identified from this group based on linkage to occupational history from National Institute for Social Security (INPS) database. Analyses were restricted to "blue collar" workers.
Comment about participation selection
Linkage to the INPS database was successful for 56.8% of cases and 57.5% of controls. Of these women, 44.3% of cases and 47.7% of controls were classified as "blue collar" and included in the analysis, which is reflected in the numbers reported above.
Exposures investigated
Occupational history since 1974 from the INPS pension fund files used to categorize individuals as having ever worked ≥ 1 year in any of 49 industrial sectors. Also collected information for each individual on industrial sector worked in for longest dur
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, province of residence
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
Among 'blue collar' workers, longest duration of employment in exposed industrial sector compared to longest duration of employment in retail/wholesale trade and services:
Iron and steel industry: aOR 1.17 (90% CI 0.98-1.40)
Electrical manufacturing: aOR 1.12 (90% CI 1.04-1.21)
Textile industry: aOR 1.08 (90% CI: 1.02-1.15)
Paper industry: aOR 1.25 (90% CI 1.06-1.46)
Press industry: aOR 1.03 (90% CI: 0.88-1.21)
Rubber industry: aOR 1.26 (90% CI 1.03-1.54)
Petroleum industry (4 cases, 6 controls): aOR 1.57 (90% CI 0.54-4.54)
Transport industry: aOR 1.29 (90% CI 0.81-2.07)
Chemical industry: aOR 1.15 (90% CI 0.99-1.34)
Agriculture: aOR 0.92 (90%: 0.75-1.11)
Alcoholic beverages and wine production: aOR 1.61 (90% CI 0.89-2.91)
Coal industry (3 cases, 2 controls): aOR 3.52 (90% CI 0.78-15.82)
Plastic industry: aOR 0.94 (0.84-1.05)
Aircraft production (2 cases, 2 controls): aOR 2.21 (90% CI 0.43-11.46)
Health care and veterinarian service: aOR 1.04 (90% CI: 0.90-1.19)

By employment duration in electrical manufacturing industry, compared to 0-4 years of employment in that sector:
5-9 years: aOR 1.04 (90% CI 0.82-1.33)
10-19 years: aOR 1.41 (90% CI 1.13-1.77)
20+ years: aOR 1.37 (90% CI 1.10-1.71)

By employment duration in rubber industry, compared to 0-4 years of employment in that sector:
5-9 years: aOR 2.81 (90% CI 1.23-6.39)
10-19 years: aOR 2.22 (90% CI 1.03-4.78)
20+ years: aOR 2.71 (90% CI 1.25-5.87)

By employment duration in dry cleaning sector, compared to 0-4 years of employment in that sector:
5-9 years: aOR 0.70 (90% CI 0.37-1.30)
10-19 years: aOR 1.29 (90% CI 0.69-2.41)
20+ years: aOR 2.29 (90% CI 0.97-5.41)
Results Comments
After adjustment for multiple comparisons, none of the associations between individual job sectors and breast cancer were statistically significant.
Author address
Department of Public Health, Experimental and Forensic Medicine, University of Pavia, Pavia, Italy. enrico.oddone@unipv.it
Reviewers Comments
A limitation to this study is lack of control for potential confounders, including breast cancer risk factors, though it is helpful that both the exposed and unexposed were classified as 'blue collar' workers. It is more likely that distributions of other breast cancer risk factors would be similar between two groups of blue collar workers than between blue collar workers and the general population or white collar workers. The authors note that important exposure information for older subjects may have been missing due to lack of job data available before 1974.