Faecal occult blood screening and reduction of colorectal cancer mortality: a case control study

To estimate the efficacy of screening on colorectal cancer mortality, a pop ulation-based case-control study was conducted in well-defined areas of Bur gundy (France). Screening by faecal occult blood test prior to diagnosis in cases born between 1914 and 1943 and who died of colorectal cancer diagnos ed in 1936-94 was compared with screening in controls matched with the case for age, sex and place of residence. Cases were less likely to have been s creened than controls, with an odds ratio (OR) of 0.67 [95% confidence inte rval (GI) 0.48-0.94]. The negative overall association did not differ by ge nder or by anatomical location. The odds ratio of death from colorectal can cer was 0.64 (95% CI 0.46-0.91) for those screened within 3 years of case d iagnosis compared with those not screened. It was 1.14 (95% CI 0.50-2.63) f or those screened more than 3 years before case diagnosis. There was a nega tive association between the risk of death from colorectal cancer and the n umber of participations in the screening campaigns. The inverse association between screening for faecal occult blood and fatal colorectal cancer sugg ests that screening can reduce colorectal cancer mortality. This report fur ther supports recommendations for population-based mass screening with faec al occult blood test.