Earlier stages of colorectal cancer detected with immunochemical faecal occult blood tests

Background: The aim of colorectal cancer screening is to improve prognosis by the detection of early cancer and precursor stages. We compared the stage distribution of asymptomatic colorectal cancer patients detected by a positive immunochemical or guaiac-based faecal occult blood test (FOBT) with symptomatic colorectal cancer patients. Methods: In a longitudinal cohort study tumour stages were assessed in 144 symptomatic (mean age 69.3 years, 56% male) and 41 asymptomatic colorectal cancer patients (mean age 64.9 years, 56% male) of which II were detected with guaiac FOBTs (G-FOBT, Hemoccult-II (R)) and 30 with immunochemical FOBTs (I-FOBT, OCSensor (R)). Stage distributions were used to calculate average stage specific predicted five-year survival rates and to analyse group differences with Wilcoxon log-rank test. Results: Colorectal cancer was detected in significantly earlier stages in symptomatic compared with asymptomatic patients (p <0.0001). Average stage specific predicted five-year survival was 59.1% in symptomatic and 76.6% in asymptomatic patients. Compared with the symptomatic patients the stage distribution for colorectal cancer patients detected with Hemoccult-II was not significantly different (p=0.29), whereas colorectal cancer was detected at significantly earlier stages with the OCSensor (p <0.0001). Treatment could be confined to colonoscopy in 27% Of the asymptomatic patients compared with 3% of the symptomatic patients (p <0.0001). Cancer distribution over the colon was comparable between symptomatic and asymptomatic patients (p=0.3) Conclusions: Compared with symptomatic patients, patients detected by FOBT and especially immunochemical FOBT, presented significantly more often at earlier stages suggesting increased survival. Additionally treatment could more often be confined to colonoscopy