New Evidence Supports Non-invasive Routine Screening And Earlier Diagnosis Of Colon Cancer

Main Category: Colorectal Cancer
Also Included In: GastroIntestinal / Gastroenterology;  Cancer / Oncology;  Radiology / Nuclear Medicine
Article Date: 05 Oct 2007 - 13:00 PDT

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New results of a pivotal study recently presented at a meeting of the American College of Radiology Imaging Network (ACRIN), showed that Computed Tomography (CT) colonography is at least as sensitive as conventional colonoscopy in detecting adenomas of 1 cm diameter or larger. Adenomas are precursors to colorectal cancer, the second most common cause of death from cancer in the EU with more than 138,000 deaths in 20001. The results of the study are expected to lead to wider adoption of CT colonography (also known as virtual colonoscopy) as routine screening for colorectal cancer. The study, funded by the US National Institutes of Health (NIH), was initiated in 2005 and has involved more than 2,500 asymptomatic patients aged 50 or over at 15 centres across the USA.

The trial compared the detection of polyps and early-stage cancer of the colon using either conventional optical colonoscopy or CT colonography, in which X-ray slice images are reconstructed by computer to provide a virtual image of the colon. Patients were investigated using both procedures and the resulting CT images were read by a panel of radiologists.

Dr Stuart Taylor of University College Hospital, London, a consultant radiologist, commented: "This very well designed study is the largest to date which has specifically investigated the use of CT colonography to screen for colorectal neoplasia in asymptomatic individuals, and has produced very positive results. The 90% sensitivity for identifying patients harbouring a 1 cm adenoma essentially validates the previously reported excellent performance of screening CT colonography by Dr Perry Pickhardt in 2003. I think we can now conclude that, when performed by appropriately trained readers, CT colonography is a viable and robust screening tool for colorectal cancer."

Colonoscopy is widely considered to be the gold-standard method of examining the colon and rectum, but it is expensive, the patient must undergo sedation, and there is a small risk of perforation of the colon, making it unsuitable for large scale population screening2.

David Sumner, Chief Executive of Medicsight, one of the industry leaders in the development of computer-aided detection (CAD) and image analysis software, said: "We welcome the results of this landmark study, confirming our belief that CT colonography is a genuine and robust option in the armamentarium that physicians have at their disposal when screening for colorectal cancer. This is likely to lead to a material increase in the use of CT colonography for screening populations who are most at risk of developing this devastating condition. Medicsight's ColonCAD™ software, which can be used with multi-detector CT imaging equipment, helps radiologists to interpret the CT scans and identify early-stage lesions."

The occurrence of colorectal cancer is strongly related to age, with 83% of cases arising in people who are 60 years or older3. Among individuals diagnosed with colorectal cancer, survival is highly dependent on how advanced the disease is at diagnosis. Five-year survival is 90% if the disease is diagnosed while it affects only the large intestine but only 65% once it has spread to the lymph nodes and 9% if it has spread throughout the body4. Most colorectal cancers arise from precursor lesions in the large intestine called 'adenomatous polyps'. Screening is important because it means that adenomatous polyps can be removed before they become cancerous. Screening also means that colorectal cancer can be diagnosed at an earlier stage4.

There are several methods currently used for colorectal cancer screening and there are advantages and disadvantages associated with all of them. CT colonography is a newer, less invasive method of examining the colon and rectum in which computed tomography is used to generate two- and three-dimensional images of the colon and rectum. Virtual colonoscopy has been found to be as effective at detecting adenomatous polyps as colonoscopy in an earlier study5.

References

1. GLOBOCAN 2000. Cancer Incidence, Mortality and Prevalence Worldwide (2000 estimates).

2. Scholefield JH. ABC of colorectal cancer: screening. BMJ 2000;321(7267):1004-6

3. Cancer Research UK. UK Bowel Cancer incidence statistics. Available here. Accessed on 12 September 2007

4. Smith RA, Mettlin CJ, Eyre H. 31. Cancer Screening and Early Detection. In: D. W. Kufe et al., eds. Cancer Medicine. 6 ed. Hamilton, London: BC Decker Inc, 2003

5. Pickhardt PJ, Choi JR, Hwang I, et al. Computed tomographic virtual colonoscopy to screen for colorectal neoplasia in asymptomatic adults. N Engl J Med 2003;349(23):2191-200

Medicsight PLC is a UK-based, research driven, leading developer of computer-aided detection (CAD) and image analysis software for the medical imaging market. The CAD software automatically highlights suspicious areas on computerised tomography (CT) scans of the colon and lung, helping radiologists to identify, measure and analyse potential disease and early indicators of disease. Medicsight's computer-aided detection (CAD) software has been validated using one of the world's largest and most population diverse databases of verified patient CT scan data. Medicsight's ColonCAD™ and LungCAD™ software products are seamlessly integrated with the advanced 3D visualisation workstations of several industry-leading imaging equipment partners.

About Computer-Aided Detection

With increasingly sophisticated radiological imaging hardware such as Multi-Detector CT scanners, radiologists are facing a growing challenge in the amount of detailed patient image data that they must review for each patient examination. Some CT scan examinations generate as many as 1000 images per patient. Review of this data by the radiologist is not only time-consuming but also prone to error due to reader fatigue. CAD software can help the reviewing radiologist by analysing the image data and automatically highlighting suspicious regions of interest for closer inspection. Without CAD software some potential abnormalities or areas of disease may be overlooked. This is critical for diagnosis and the management of patient outcomes as early detection of disease greatly increases the probability of successful treatment and a positive therapeutic outcome.

About Medicsight's CAD software

Medicsight's ColonCAD™ and LungCAD™ software use an advanced CAD algorithm to analyse CT scans of the colon and lung and automatically highlight suspicious areas that may be indicators of disease. CAD may highlight areas easily overlooked by the reviewing radiologist, such as small lesions or regions that are hidden from view behind folds in the colon or normal structures and surrounding tissue in the lung.

Both CAD products seamlessly integrate with the advanced 3D visualisation platforms of industry-leading imaging equipment partners. The integrated systems provide sophisticated image viewing capabilities, including 3D reconstructed image data, with the added advantage of demonstrating automatic CAD findings to assist clinical end users in the detection and analysis of disease. This allows clinical end users to perform either a 'second read', where CAD findings are displayed to the user after completion of an initial review of the CT scan data, or a 'concurrent read' where CAD findings are displayed during the user's initial review of the original CT scan images.

Since inception, Medicsight has developed close and lasting relationships with some of the world's foremost clinicians in product related areas. This provides the Company with a wealth of clinical expertise and dedicated clinical research to support ongoing product development. Medicsight also collaborates with a number of leading academic institutions and clinical research programmes worldwide to develop the Company's comprehensive database of population diverse verified patient CT scan data, thus allowing Medicsight's products to be validated to the highest possible standards.

About ACRIN

The American College of Radiology Imaging Network (ACRIN) is a national cancer research organization sponsored and funded by the US National Cancer Institute.

About adenomas

An adenoma (sometimes known as a polyp) is a slow-growing benign tumour. This is the most common type of early-stage tumour found in the colon and typically projects into the colon from the wall. Adenomas are routinely removed on identification because of their tendency to become malignant.

http://www.acrin.org/