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Laser test for cancerous polyps avoids pathology delays

Project Lead
Dr Venkat Subramaniam, Consultant Gastroenterologist at Leeds Teaching Hospitals

The technology

The WavSTAT Optical Biopsy System®, developed by San Diego- based medical device company, SpectraScience, connects a fibre optic probe to standard endoscopic biopsy forceps. The device shines light onto the polyp and analyses the fluorescence reflected back from the tissue. Depending on the wavelengths of reflected light detected, the system can determine if the polyp is pre-cancerous or benign and informs the clinician of the result.

Most patients who undergo a screening colonoscopy are classed as low, medium or high risk of developing subsequent polyps or colon cancer based on the number and size of pre-cancerous polyps found. The majority of polyps found during colonoscopy are usually benign, though all are usually removed for histological confirmation. Cancerous lesions usually look very distinctive, but it’s difficult to distinguish between benign and pre-cancerous polyps visually. For this reason, all polyps have to be sent off for histopathological analysis, which can take up to two weeks. Depending on the number and size of pre-cancerous polyps detected , patients are then scheduled for their next follow-up colonoscopy.

Providing immediate feedback to patients would limit their anxiety, improve their care by allowing their next follow up to be decided on the spot and lower costs by reducing the need for laboratory analysis. It may also be possible in the future to agree protocols which allow polyps diagnosed as benign to be left in place, thereby reducing unnecessary interventions.

Our role

SpectraScience was keen to find a UK centre to take part in a Europe-wide multi-centre trial to test the accuracy of the WavSTAT technology. The company approached the NIHR Office for Clinical Infrastructure, who put them in touch with the Colorectal HTC.

With our help, SpectraScience met with Dr Venkat Subramanian, Associate Professor and Consultant Gastroenterologist at St James University Hospital, who has a particular expertise and research interests  in imaging technologies in endoscopy. As a result, Leeds became the trial’s only UK centre and has, to date, recruited over 60 patients and submitted close to 140 polyps as part of an overall Europe-wide target of 1200. Each polyp is diagnosed during endoscopy using WavSTAT, then sent to two separate pathologists for laboratory analysis – all three diagnoses being reached independently. If the two pathologists reach the same diagnosis, the polyp is submitted into the trial.

Next steps

The trial, now nearing completion, will provide data on the accuracy of diagnosis using WavSTAT, as compared to laboratory analysis.  The American Society of Gastrointestinal Endoscopy guidelines require a negative predictive value of 90 per cent for the test to be clinically appropriate. A high negative predictive value means that if the test predicts that the polyp is benign then it is highly likely to diagnosed as benign by the histopathologist as well. This would reduce the risk of missing out any pre-cancerous polyps.

Further work will be needed to assess potential cost savings for the NHS and how well the technology enables clinicians to set appropriate follow up schedules. Further UK trials are also likely to be required to ensure the technology can be used effectively by the different kinds of endoscopy centres that exist in the UK.