Prevention of advanced colorectal cancer by screening using the immunochemical faecal occult blood test: A case-control study

Abstract

To evaluate colorectal cancer screening with faecal occult blood testing (FOBT) in terms of prevention of advanced cancers, we conducted a case-control study in the areas where an annual screening programme with immunochemical FOBT has been offered to all inhabitants aged 40 years or over. Cases were 357 consecutive patients in the study areas clinically diagnosed as having advanced colorectal cancer or a tumour invading the muscularis propriae or deeper, that is, T2-T4 in TNM classification. Three controls were selected for each case matched by gender, age, residential area and exposure status to screening within 1 year before case diagnosis. The odds ratios (ORs) of developing advanced cancer were calculated using conditional logistic regression analyses. The OR for those screened within 3 years before the diagnosis vs those not screened was 0.54 (95% confidence interval (Cl) 0.29-0.99). The ORs were lower for rectum than for colon (0.32-0.73 and 0.84-1.18 for rectum and colon, respectively). For those screened within the past 3 years, OR, of developing advanced cancer in the rectum was 0.32 (95%Cl: 0.12-0.84). A screening programme with immunochemical FOBT can be effective for prevention of advanced colorectal cancer. Risk reduction appears to be larger for rectal than for colon cancer. © 2003 Cancer Research UK.