Prostate cancer and workplace exposures

Workplace exposures and prostate cancer: analysis and reporting on a Canadian population-based study

PI: Marie-Elise Parent
Co-Applicants: Paul Demers, Jérôme Lavoué, Marie-Claude Rousseau, Andrea Benedetti, Cheryl Peters
Collaborators (Knowledge Users): Canadian Cancer Society, Cancer Research Society, CAREX Canada, Cancer Care Ontario – Occupational Cancer Research Centre
Period: October 2018 – September 2022 (4 years), $608,176

Rationale: Each year, 21,000 Canadian men are diagnosed with prostate cancer (PCa). About 30% of these are aggressive but diagnosis and treatment of non-aggressive ones seriously impact quality of life. Age, ancestry and family history are the only established risk factors while genetics explain only a proportion of familial cases. There is compelling evidence that environmental factors play a role, but modifiable risk factors have yet to be identified so prevention has not been possible. Other than for pesticides, very little research has been conducted on environmental chemicals in PCa etiology. Several chemicals are themselves carcinogens or act as hormone modulators, and could be implicated. The workplace represents a preferential window to study these since many are encountered there at higher levels, facilitating their measurement. Since most workplace chemicals eventually make their way into the general environment, such exposures are not only relevant to workers but also to the entire population. The absence of large occupational studies benefiting from strong exposure assessment has been the major drawback to advancing knowledge in this area. In 2002-2015, Canadian funding agencies funded what is to our knowledge the largest and most comprehensive population-based study of PCa, to assess the etiological role of workplace exposures. The occupational assessment was completed, as planned, in late 2015, coinciding with the end of funding, and it was anticipated that new funding would need to be secured for primary analyses. CIHR funding is sought at this time to leverage this large effort and investment, and carry out primary analyses and report on this unparalleled Canadian resource.
Broad goal: To investigate whether different exposures measured in the workplace increase the risk of developing PCa.

Methods: 1,933 cases, including 538 aggressive cancers, were ascertained from Montreal metropolitan area hospitals. Concomitantly, 1,994 population controls were selected from electoral lists. Face-to-face interviews collected information on socio-demographic, lifestyle and medical factors, including screening. We documented each job held by each subject over his lifetime, eliciting details on specific tasks, equipment used, etc. This wealth of occupational information (15,724 job descriptions) has been coded by a team of chemists/industrial hygienists into lifetime exposure to hundreds of chemicals.
Aims: This protocol outlines 19 analytical subprojects to be undertaken over the course of the grant. It focuses on suspected exposures with hormone-modulating properties and/or previous evidence such as polycyclic aromatic hydrocarbons, petroleum-derived liquids, engine emissions and combustion products, solvents, welding fumes, resins and polymers, metals, painting-related chemicals, and pesticides. Other projects focus on night work and on physical activity/inactivity at work. Exposures will be analysed individually and combined, taking into account co-exposures, confounding and interactions.
Core expertise: We propose here an exciting, innovative and far-reaching data analysis project, benefiting from a solid expertise in occupational epidemiology, exposure assessment and biostatistics, and involving trainees.
Significance/application: This project, representing a major advance in the field, will generate important new knowledge towards the establishment of preventive measures against PCa.