In Canada, prostate cancer is the most commonly diagnosed cancer among men [1]. Important risk factors for prostate cancer include age and family history, however, little is known about the modifiable risk factors for the disease, including occupational causes. Occupational exposures that affect the endocrine system, such as shift work, are of particular interest given that prostate cancer can be a hormone-sensitive malignancy. Occupational patterns of prostate cancer risk have has been a major area of research for the Occupational Cancer Research Centre [2–5]
Possible occupational risk factors
These work-related exposures are possible risk factors for prostate cancer, but evidence is currently inconclusive.
The greatest risks of prostate cancer were observed among transportation, firefighting, police occupations, and white collar occupations. Pesticide exposure among agricultural workers has been previously explored as a potential prostate cancer risk factor [15]. No excess risk was observed among these workers in the ODSS.
Employment in transportation industries and occupations was associated with an increased risk of prostate cancer. Possible exposures in these groups include sedentary behavior and physical inactivity, shift work, obesity, and whole body vibration. Exposure to whole body vibration occurs when mechanical energy from vibrating surfaces is passed to the body either in standing or sitting positions. The role of whole body vibrations in prostate cancer etiology remains unclear, but other prostate conditions like prostatitis and increasing testosterone levels have been linked to whole body vibration exposure [14]. Circadian rhythm disruption and cosmic radiation among airline flight personnel has been posited as a potential prostate cancer risk factor [7].
Elevated risks of prostate cancer were observed for metal-related occupations such as metal processing, metal machining, metal shaping and forming, and metal product fabricating and assembling. These types of jobs may expose workers to elevated levels of possible risk factors for prostate cancer metallic compounds such as cadmium and chromium, which can be components of metal alloys [7,16].
Elevated risk of prostate cancer is observed in both firefighters and police. This has been consistently observed in other studies and could be related to shift work, sedentary behaviour, or high levels of occupational stress among these groups [2]. Firefighters may also be exposed to diesel engine exhaust while working in fire halls, which is a potential risk factor for prostate cancer.
We observed an increased risk of prostate cancer among several occupations in medicine and health, which may be attributable to shiftwork. A possible excess risk has been in relationship to radiation [6]. However, no excess risk was observed among nurses, and there is no conclusive evidence of an association between exposure to ionizing radiation and prostate cancer [7].
* This group includes occupations, not elsewhere classified concerned with nursing, therapy and related assisting occupations, including providing supportive services in diagnostic and therapeutic procedures.
Increased risks of prostate cancer were observed across all management and administrative occupations, as well as in teaching occupations. This may be related to sedentary behavior and low occupational physical activity in white collar work. Additionally, these findings could relate to a greater participation in prostate cancer screening in this group relative to others [17].
Increased prostate cancer risk was observed for certain mechanics and repairers and electrical workers. Potential prostate cancer risk factors are unclear.
Figure 1. Risk of prostate cancer diagnosis among 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 2. Risk of prostate cancer diagnosis among workers employed in each occupation group relative to all others, Occupational Disease Surveillance System (ODSS), 1983-2016
