Increased Odds of Interval Left-Sided Colorectal Cancer After Flexible Sigmoidoscopy Compared With Colonoscopy in Older Patients in the United States: A Population-Based Analysis of the SEER-Medicare Linked Database, 2001-2005

In older patients with left-sided CRC, the odds of interval CRC after flexible sigmoidoscopy was 3 times as high as that after colonoscopy. Whether this finding reflects differences in bowel preparation quality, sedation use, or depth of insertion warrants future research.