Breast cancer is the most commonly diagnosed cancer in women, but accounts for less than 1% of cancer cases in men worldwide [1]. There is strong evidence linking female breast cancer to estrogen (e.g. hormone therapy, early menarche, late menopause, few pregnancies), obesity and physical inactivity, and alcohol consumption, but much less is known about potential occupational risk factors. Research on potential occupational risk factors for breast cancer has generally focused on exposure to some organic solvents and pesticides, polychlorinated biphenyls (PCBs), and shift work. Endocrine disrupting agents are suspected due to the role of hormones in breast cancer. Most evidence regarding breast cancer risk factors is based on female breast cancer due to the rarity of the disease among males. There have been few studies of occupational risk factors for male breast cancer and results have been somewhat inconsistent, but insights regarding occupational risk factors could impact both women and men.
Known occupational risk factors
Possible occupational risk factors
Increased risks of breast cancer were observed among both women and men for some occupational groups in the ODSS, which suggests a role for work-related risk factors in breast cancer etiology.
Elevated risks of breast cancer have previously been observed in workers involved in night or rotating shift work, including nurses [3]. Increased risk of breast cancer was observed among both male and female nurses in the ODSS. Health care workers such as radiological technicians may be exposed to x-ray and gamma radiation through medical imaging and radiation treatments [3]. Ethylene oxide, a suspected risk factor for breast cancer, is a chemical used in the sterilization of medical and dental equipment [6].
*This industry includes laboratories (dental, medical, X-ray, etc.) providing analysis, diagnosis or treatment service to the medical or dental professions or to patients on prescription of a physician or dentist, and organizations such as the Victorian Order of Nurses, Red Cross Blood Transfusion Service, and St. John Ambulance.
Risk of breast cancer among airline crew has been of interest because of exposure to cosmic radiation and circadian rhythm disruption [4]. Too few cases were observed among workers in the ODSS to examine this risk among specific occupation groups, or among men, but an increased breast cancer risk was observed among women for the overall industry.
Individuals in these occupations generally have higher income and education, fewer children and work in sedentary jobs, which are characteristics that have been associated with breast cancer among women [7]. Elevated risks were observed among both men and women for many of these occupational groups.
Figure 1. Risk of breast cancer diagnosis among female workers employed in each industry group relative to all others, Occupational Disease Surveillance System (ODSS), 1983-2016
The hazard ratio is an estimate of the average time to diagnosis among workers in each industry/occupation group divided by that in all others during the study period. Hazard ratios above 1.00 indicate a greater risk of disease in a given group compared to all others. Estimates are adjusted for birth year and sex. The width of the 95% Confidence Interval (CI) is based on the number of cases in each group (more cases narrows the interval).
Figure 3. Risk of breast cancer diagnosis among female workers employed in each occupation group relative to all others, Occupational Disease Surveillance System (ODSS), 1983-2016
Figure 2. Risk of breast cancer diagnosis among male workers employed in each industry group relative to all others, Occupational Disease Surveillance System (ODSS), 1983-2016
Figure 4. Risk of breast cancer diagnosis among male workers employed in each occupation group relative to all others, Occupational Disease Surveillance System (ODSS), 1983-2016
