Optical Polyp Testing for In Vivo Classification

Polyps detected during a colonoscopy may range from benign to precancerous and cancerous. While experienced endoscopists can reliably recognise cancer, the difference between small polyps that have the potential to develop into cancer (adenomas) and those that do not (hyperplastic), is often ambiguous. The standard approach is to simply remove all polyps and analyse them in the histology lab. This means that many patients with hyperplastic polyps (40% of those detected) are unnecessarily exposed to risk of injury (bowel perforation and bleeding) during removal. Furthermore the NHS faces the significant cost of diagnosing this harmless colon tissue. If clinicians were able to accurately determine polyp type during endoscopy, without removal, then hyperplastic tissue could be left alone while potentially harmful tissue is removed.

A pilot study of a new endoscopic optical imaging probe (OPTIC), which analyses how different colours of light interact with tissue, is proposed. Previous research has indicated that these properties differ in hyperplastic and adenomatous polyps. The probe is contained within a normal endoscope and uses white light and blue/violet laser light to illuminate the tissue. The reflected and fluorescent light emitted, along with normal colour pictures of the polyp surface, are measured and recorded to quantify specific characteristics of each type.

Patients attending endoscopy clinics at Imperial College Healthcare NHS Trust will be asked to allow the use of the OPTIC probe during their colonoscopy. If the clinician detects a polyp that he/she intends to remove then this will be analysed using OPTIC before removal. The histology results from the tissue sample will be recorded and correlated to the OPTIC probe measurements. The resulting library of optical data will be used to design software to automatically categorise unknown polyps based on the OPTIC signal. The accuracy of the technique will be compared to the clinicians' visual assessments. The patients' involvement in the study ceases after the colonoscopy.

Inclusion criteria

• All patients attending for screening colonoscopy, urgent colonoscopy for altered bowel habit (on a two week wait) or those patients attending for polyp surveillance or therapy.

Exclusion criteria

• Patients with colitis, familial adenomatous polyposis or those that have undergone previous surgery as these different pathologies may confound interpretation of the optical signals.
• At the discretion of the endoscopist patients with poor bowel preparation will be excluded if it is judged that the colonoscopy cannot be completed. Further quality measures will be determined for reliable data acquisition (see outcome measures).
• Patients with acute gastrointestinal bleeding
• Patients with chronic liver disease
• Patients with abnormal coagulation or any other contra-indication to use of standard biopsy in routine diagnostic endoscopic procedures
• Patients who are unable or unwilling to give informed consent
• Patients under the age of 18 years
• Patients unable to speak English