Objectives The etiology of
male breast cancer (MBC) is largely unknown but a causal role of exposure to organic
solvents has been suggested. Previous studies on occupational risk factors of
breast cancer were often restricted to women who are frequently exposed to lower levels and at a lower frequency than men. We investigated the association between MBC and occupational exposure to
petroleum and oxygenated and chlorinated
solvents in a multicenter case-control study of rare
cancers in Europe. Methods The study included 104 MBC cases and 1901 controls. Detailed lifetime work history was obtained during interviews, together with sociodemographic characteristics, medical history and lifestyle factors. Occupational exposures to
solvents were estimated from a job-exposure matrix. Odds ratios (OR) and their 95% confidence intervals (CI) were calculated using unconditional logistic regression models. Results Lifetime cumulative exposure to
trichloroethylene >23.9 ppm years was associated with an increased MBC risk, compared to non-exposure [OR (95% CI): 2.1 (1.2-4.0); P trend <0.01). This increase in risk persisted when only exposures that occurred ≥10 years before diagnosis were considered. In addition, a possible role for
benzene and
ethylene glycol in MBC risk was suggested, but no exposure-response trend was observed. Conclusions These findings add to the evidence of an increased risk of
breast cancer among men professionally exposed to
trichloroethylene and possibly to
benzene or
ethylene glycol. Further studies should be conducted in populations with high level of exposure to confirm our results.