The purpose of this study is to compare the adenoma detection rates of full-spectrum endoscopy versus standard forward-viewing colonoscopy in colorectal cancer screening programme.

Colorectal cancer is the third most common neoplasia and the second leading cause of cancer death in West countries. Colonoscopy is the gold standard for prevention of colorectal cancer disease. Screening for colorectal cancer with biennial faecal occult blood testing is a widely used strategy followed by colonoscopy for those with a positive test. Colonoscopy identifies polyps during the procedure as well as polyp removal in order to prevent progression to cancer. Although, interval cancer appears after a colonoscopy because of 22-28% of polyp missed rates. Advanced Technology may improve adenoma detection rates so decrease interval cancer and reduce mortally. Full-spectrum endoscopy with 330º angle vision decrease adenoma miss rate in general population.

The investigators conducted a randomized trial in patients from colorectal cancer screening programme (aged 50-69 years) after faecal immunological test positive. One arm the colonoscopy is performed with standard forward view colonoscopy (170º angle view) and the other arm is performed with full-spectrum endoscopy (EndoChoice) (330º angle view)

Inclusion Criteria:

• patient referred for colorectal cancer screening with positive fecal inmunological test.
• Age between 50 and 69 years

Exclusion Criteria:

• history of colonic resection,
• high risk for colorectal cancer like family history of colorectal cancer o polyposis syndrome,
• inflammatory bowel disease,
• patients with lower gastrointestinal bleeding symptoms,
• acute diverticulitis,
• colonic strictures,
• poor bowel preparation (Boston scale less than 5 points)