- Geir Hoff, professor12,
- Michael Bretthauer, professor 2345,
- Kjetil Garborg, consultant4,
- Tor Jac Eide, professor2
- 1Telemark Hospital, Skien, Norway
- 2University of Oslo, Norway
- 3Oslo University Hospital, Oslo, Norway
- 4Sørlandet Hospital, Kristiansand, Norway
- 5Harvard School of Public Health, Boston, USA
- Correspondence to: G Hoff
Screening programmes for colorectal cancer aim to detect early colorectal cancer and benign lesions with malignant potential, such as adenomas, before symptoms develop. Screening has been shown to reduce mortality from colorectal cancer by 16% when faecal occult blood testing is used1 and by 28% with flexible sigmoidoscopy.2 Colonoscopy is the standard follow-up examination after positive screening using either flexible sigmoidoscopy or faecal occult blood tests. This has increased the demand for colonoscopy services internationally to provide definitive, detailed assessment of the colon and often to remove benign lesions.
Although removal of cancerous lesions is uncontroversial, there is debate and uncertainty about how to manage benign lesions. Expansion of screening programmes and the development of new technology that can detect inconspicuous polyps of unknown clinical importance increase the need for clear evidence on the natural course of polyps and their management. This is particularly important for serrated polyps, which are less understood and often more risky to remove than adenomas. Recent guidelines recommend removal of all serrated lesions except those in the sigmoid colon or rectum that are <5 mm in diameter,3 but evidence that the risks of removal are outweighed by the benefits is lacking.
Not all polyps are equal
Polyps can be classified to help predict their malignant potential. Although some features can be identified macroscopically—for example, pedunculated (stalked) polyps can be differentiated from sessile (flat) polyps—definitive classification requires microscopic examination of histology and cellular dysplasia. This means that the polyp must be removed.
The most common polyps found on screening are adenomas. Although …