The study found that the men who developed prostate cancer were less likely to hold the more physically active jobs. Those that got cancer also were more likely than the control group to be highly exposed to the chemicals that were evaluated, including hydrazine, benzene, mineral oil, polycyclic aromatic hydrocarbons (PAHs) and trichloroethylene (TCE), which are known or suspected carcinogens.
The findings are supported by other studies that suggest continuous physical activity, but not intermittent activity, is required to lower the risk of prostate cancer. The biologic mechanisms by which physical activity lower prostate cancer risk have not been identified, although some experts have speculated that activity can alter hormone levels in some men.
A strength of the UCLA study was that researchers used personnel records, job description manuals, industrial hygiene review and retired worker interviews to develop their job exposure matrix, avoiding problems with study subject recall and interviewer bias. Researchers also were able to obtain cancer incidence data and did not have to rely on mortality data. Prostate cancer is largely non-fatal, so mortality rates would not have been good data to analyze, Ritz said.
The study was limited in that researchers were not able to account for other potential factors that might affect prostate cancer risk, such as recreational physical activity and diet, said Anusha Krishnadasan, an epidemiologist at Olive View-UCLA Education and Research Institute and fi
|Contact: Kim Irwin|
University of California - Los Angeles