Physical job activity may cut prostate cancer risk

By Joene Hendry

NEW YORK (Reuters Health) - Working in a job that requires a continuous level of high physical effort may decrease the likelihood of a man developing prostate cancer, researchers report.

Previous research suggested that physical activity decreases the risk of certain cancers. "This study supports this finding for prostate cancer," Dr. Anusha Krishnadasan, at the University of California, Los Angeles, told Reuters Health.

Krishnadasan and colleagues looked at the link between prostate cancer and physical activity among men working at a southern California facility that tested aerospace engines and nuclear power systems.

The investigators compared the physical activity requirements of 392 workers who developed prostate cancer with 1,805 men similarly employed and of similar age.

The odds for prostate cancer among aerospace workers involved in highly physically active jobs were 45 percent lower than among less active co-workers, after adjusting for variables such as work-related exposure to suspected carcinogens, age at the start of employment and at diagnosis, and pay status, the researchers report in the journal Cancer Causes Control.

By contrast, the odds for prostate cancer did not differ significantly among nuclear power workers involved in high versus low levels of physical activity at work.

The team suggests that differences in the level of continuous, as opposed to intermittent, physical activity required by aerospace and nuclear power workers may explain these findings.

Aerospace workers were primarily (64 percent) mechanics and technicians, or welders, assemblers, and machinists involved in work that required sustained and high levels of physical activity. Just 34 percent of the nuclear power workers held similar job titles, while another 31 percent performed jobs such as patrolmen, firemen, and electricians that only involved intermittently high levels of physical activity.

However, these findings should be confirmed in follow-up studies that take a more in-depth look at other factors that might influence the association, Krishnadasan and colleagues note.

SOURCE: Cancer Causes Control, February 2008.