May 2010
Patients with suspected colon cancer face less invasive tests, thanks to research funded by UCLH Charity

Experts from the imaging and endoscopy departments at University College London Hospital and the Institute of Nuclear Medicine have teamed up to develop a non-invasive technique to diagnose colorectal cancer and polyps.

Research funded by the UCLH Charity found that using a combination of Computerised Tomography Colonography (CTC) scanning and Positron Emission Tomography (PET) scanning detected abnormalities as effectively as using an investigative camera.

"Colorectal cancer is one of the leading causes of cancer death in the Western world" says Dr Stuart Taylor, Reader in Clinical Imaging at UCLH. "It affects around six per cent of the population and the first indication is often the presence of polyps, abnormal tissue growths on the inner lining of the colon or large intestine.

"Up to now the standard diagnostic test for colorectal cancer and polyps has been colonoscopy, whereby a telescopic camera is introduced into the colon via the back passage and passed around the one to two metres of colon to look for abnormalities in the bowel lining.

"Although this technique is very effective, it is also invasive and can be very uncomfortable for patients as they need to empty their bowel using laxatives beforehand, often require sedation during the test and need to take a whole day off their normal activities."

Keen to find a less invasive way of detecting abnormalities, the team set up a study to test the effectiveness of using a combination of CTC and PET scans. Fifty-six patients agreed to undergo a one-hour CTC and PET scan about two weeks before their scheduled colonoscopy. This was done without the use of laxatives.

Patients were also asked to complete a questionnaire to see how they tolerated the tests and which ones they preferred.

The colonoscopy results were then compared with the CTC scan on its own and with the CTC and PET scans combined.

Impressive results

The research team found that the combined PET CTC scans detected all the important larger polyps found by the invasive colonoscopy technique. In addition, most patients found the combined scan technique more comfortable and preferred it to colonoscopy.

"As well as being non-invasive, the PET CTC scans were effective even when patients had not used laxatives, which is a great advantage as they can be harmful to older patients if they cause dehydration and disturb their salt levels" says Dr Taylor.

Figs-ABC

"The CTC scan provides images of the lining of the bowel, which has been gently distended with gas, without the need for sedatives. The PET scan, which is a relatively recent innovation, produces further images based on how much blood sugar (glucose) the body tissue has absorbed. Because cancerous cells tend to take up more blood sugar than normal tissue, these concentrations provide clear evidence of any abnormalities.

"Thanks to our study, which was made possible by funding from the UCLH Charity, we are now able to offer combined PET CTC scanning to patients with suspected colorectal cancer, providing them with a less invasive but equally accurate diagnostic test."