Colorectal cancer (CRC) screening using sigmoidoscopy followed by colonoscopy: a feasibility and efficacy study on a cancer institute based population.

Background: Advanced distal neoplasia found at sigmoidoscopy could be the marker for more proximal lesions.
Patients and Methods: In the setting of a screening clinic, subjects underwent flexible sigmoidoscopy. If no significant lesion was found, sigmoidoscopy was planned after 5 years. If an advanced neoplasia was found, colonoscopy was performed just after the first sigmoidoscopy and at 1, 3 and 5 years. If a non-advanced neoplasia was found, sigmoidoscopy was performed at 1, 3 and 5 years and followed by colonoscopy if advanced lesion was found.
Results: At first screening 1704/1912 (88%) subjects had a negative sigmoidoscopy, 104 (5.4%) had an advanced neoplasia, 96 (6%) had a non-advanced neoplasia and eight (0.4%) had invasive colorectal cancer (CRC). At follow-up examinations at 1, 3 and 5 years, among 170 subjects with advanced and non-advanced neoplasia, one developed invasive CRC and 47 (31.6%), advanced neoplasia. At 5 years, among 718 first negative sigmoidoscopies, 572 (80%) were confirmed negative and 97 (14%) had advanced neoplasia. Colorectal cancer status at 5 years could be checked for interval cancers in 97% of subjects and no CRC was diagnosed in subjects who did not attend sigmoidoscopy at 5 years. Comparison of the incidence of invasive CRC to the data of registries of the Netherlands and Luxembourg suggested that the incidence of CRC was decreased by 36%-46%. Seven of the nine CRCs were Duke's A and the two others were Duke's B and C.
Conclusions: Screening with sigmoidoscopy followed by colonoscopy in case of positive sigmoidoscopy leads to substantial decreases in the incidence of CRC. Most CRCs found are at an early, curable stage of their development.