Abstract
In order to elucidate the effectiveness of colorectal cancer screening, we compared 5-year relative survival rates between screening-detected and clinically diagnosed colorectal cancer. Between 1984 and 1996, 9,554 cases of colorectal cancer were registered to the Fukui Prefectural Cancer Registry. After excluding 3,151 cases of which the information was derived only from death certificates or not able to be followed-up, we analyzed 6, 240 cases (362 mass screen-detected and 5,878 clinically diagnosed cases). The relative survival rates were analyzed through Ederer-II method with the log-rank test. The relative survival rates were significantly higher in mass screening-detected groups than in clinically diagnosed groups with same depth of lesions, same clinical stages and same histological types. We also observed significant survival benefit in mass screening detected groups for 50-79 years of age. These results suggest that mass screening using immunochemical fecal occult blood test makes it possible to reduce mortality from colorectal cancer.
