Background: To investigate prospectively the association between colorectal cancer screening and subsequent risk of colorectal cancer death in a large-scale population-based cohort study (the JPHC study) with a 13-year follow-up period in Japan.
Methods: We analyzed data from a population-based cohort of 42,150 (20,326 men and 21,824 women) subjects. Subjects who had undergone fecal occult blood test (FOBT) screening during the preceding 12 months were defined as the screened group. A total of 132 colorectal cancer deaths and 597 cases of newly diagnosed colorectal cancer were identified during the follow-up period.
Results: We observed a nearly 70% decrease in colorectal cancer mortality in screened versus unscreened subjects (RR=0.28, 95% CI=0.13-0.61). Screening participation was associated with a 30% reduced risk of death from all causes other than colorectal cancer (RR=0.70, 95% CI=0.61-0.79). However, the extent of mortality reduction was greater for colorectal cancer than other causes. A significant decrease in the incidence of advanced colorectal cancer was seen in screened subjects (RR=0.41, 95% CI=0.27-0.63), although the overall incidence rate did not differ significantly between the screened and unscreened groups.
Conclusion: Although self-selection bias could not be fully controlled, these findings suggest that colorectal cancer screening may be associated with a reduction in mortality from colorectal cancer in the Japanese population.