Female breast cancer in Lombardy, Italy (2002-2009) : a case-control study on occupational risks

BACKGROUND: The role of occupational exposures in breast cancer development is still uncertain and, to our knowledge, no studies have been recently carried out in Italy to provide a comprehensive estimation of this possible risk. METHODS: Based on administrative data, a case-control study was carried out recruiting all incident cases of female breast cancer in the period 2002-2009, aged between 35 and 69 years, residing in Lombardy, Italy. Controls were randomly sampled from all women residing in Lombardy as of December 31, 2005. Occupational histories, including blue-collar status, were available from 1974 through record linkage with a social security pension database, and were obtained for 11,188 cases and 25,329 controls. Adjusted odds ratios (ORs) and corresponding 90% confidence intervals (CIs) were calculated using multiple unconditional logistic regression models, including terms for sectors of longest employment and for duration of employment. Multiple comparisons were accounted for according to the Benjamini-Hochberg method. RESULTS: The ORs for female breast cancer were modestly but significantly increased for employment in electrical manufacturing (OR 1.12, 90%CI 1.04-1.21), textile (OR 1.08, 90%CI 1.02-1.15), paper (OR 1.25, 90%CI 1.06-1.46) and rubber (OR 1.26, 90%CI 1.03-1.54) industries. Analysis by duration of employment within sectors showed significantly increased ORs for electrical manufacturing and rubber industries. After adjustment for multiple comparisons no estimates remained statistically significant. CONCLUSIONS: Although with several limitations, our results point to a possible role of exposures in electrical manufacturing, textile, paper and rubber industries in the process leading to breast cancer. An in-dept study for the electrical manufacturing industry has been already planned.