A physically active job may lead to more than a better condition: it may lower the risk of developing prostate cancer, as found by a research carried out by a team at UCLA's Jonsson Cancer Center and published in the journal "Cancer Causes Control." The study was made on 2,100 men, ex-employees at the Rocketdyne facility in the San Fernando Valley, who had had jobs that exposed them to radiation and chemicals, factors known to boost certain cancers. 362 subjects had developed prostate cancer, between January 1988 and January 1999.

"The message from this study for today is that if you're more active, you may be able to prevent this cancer from happening. If you have a desk job, do something physically active to counterbalance it," said senior author Beate Ritz, a Jonsson Cancer Center researcher, and an associate professor of epidemiology in the UCLA School of Public Health.

The team assigned the ex-employees to jobs with low, moderate and high amounts of exertion. Low physical activity jobs meant managers, supervisors, analysts, administrators and senior engineers. Moderate physically active jobs were considered senior mechanics and technicians, inspectors and engineers. High physical activity jobs meant masons and bricklayers, metal fitters, welders, packers, painters, tool and die makers, truck drivers, lift operators and janitors.

The subjects who developed prostate cancer were more likely to have a low physically active job. Compared to the control group, they were also more likely to have been exposed to some carcinogen chemicals, like hydrazine, benzene, mineral oil, polycyclic aromatic hydrocarbons (PAHs) and trichloroethylene (TCE). The research strengthens the results of other studies, pointing that continuous, but not intermittent, physical activity cuts down the risk of prostate cancer. The biologic mechanisms behind this are not know, but it could be connected to hormone levels.

"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," said Ritz.

"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. All we can say for sure is that aerospace workers that were highly active on a regular basis for many years while working at Rocketdyne were at a decreased risk of prostate cancer," said first author Anusha Krishnadasan, an epidemiologist at Olive View-UCLA Education and Research Institute.

Other researches pointed as risk factors for prostate cancer the family history of the disease and an increased frequency amongst African Americans.