Research appearing in the September, 2006 issue of the American Journal of Epidemiology links working rotating shifts to an increased incidence of prostate cancer. People who work rotating shifts have been known to have increased risk in some cancers, like breast cancer and colon cancer. This study looked at over 14,000 Japanese workers in the Japan Collaborative Cohort Study for Evaluation of Cancer Risk. It found that there was a three-fold increase in the incidence of prostate cancer in those working rotating shifts compared to those who did not.