Efficacy of Segmental Examination Twice of the Proximal Colon on Adenoma Detection

Colonoscopy is the gold standard screening test for colorectal cancer (CRC). Removal of adenomas can reduce the incidence and mortality of CRC. However, there is evidence that some patients may develop interval cancers-cancers developed within 3-5 years following colonoscopy and polypectomy. The overall rate of interval cancer was 1.1-2.7 per 1000 person-years. Several studies have suggested that patients who develop interval cancers are more likely to have proximal compared than distal cancers.

One hypothesis is that adenomas may be more likely to be missed in the proximal colon compared with the distal colon. Serrated polyps and some adenomas in the proximal colon may be difficult to detect if they are flat, covered with mucus, or behind folds. A second hypothesis is that neoplastic lesions of the proximal colon may biologically differ from distal lesions and progress to malignancy with a short dwell time.

Several tandem back to back colonoscopy studies have demonstrated that up to 27% adenomas in the proximal colon are missed during routine screening colonoscopy. Hover, examining the colon twice as that in the back to back studies is difficult to be performed in clinical practice. Thus, we developed a novel colonoscopy technique, segmental examination twice of the proximal colon, that is simple and easy to be performed. The current study aims to examine the efficacy of segmental examination twice of the proximal colon on adenoma detection rate (ADR) during routine screening and surveillance colonoscopy.

Inclusion criteria

• Asia-Pacific Colorectal Screening score ≥2, such as patients ≥ 50 years, patients with a family history of colorectal cancer in a first-degree relative or male patients with current or past smoking.

Exclusion criteria

• Patients with prior resection of the proximal colon, advanced colonic cancer, inflammatory bowel disease, or polyposis syndrome.
• The cecum could not be intubated.
• Inadequate bowel preparation (Boston Bowel Preparation Scale score <2 in any segment of the colon).
• Biopsies were not available.
• Unable to provide informed consent.