CT colonography: current status and future promise

Colorectal Cancer Biomarkers: Where Are We Now?

Colorectal cancer is one of the major causes of cancer-related death in the Western world. Patient survival is highly dependent on the tumor stage at the time of diagnosis. Reduced sensitivity to chemotherapy is still a major obstacle in effective treatment of advanced disease. Due to the fact that colorectal cancer is mostly asymptomatic until it progresses to advanced stages, the implementation of screening programs aimed at early detection is essential to reduce incidence and mortality rates. Current screening and diagnostic methods range from semi-invasive procedures such as colonoscopy to noninvasive stool-based tests. The combination of the absence of symptoms, the semi-invasive nature of currently used methods, and the suboptimal accuracy of fecal blood tests results in colorectal cancer diagnosis at advanced stages in a significant number of individuals. Alterations in gene expression leading to colorectal carcinogenesis are reflected in dysregulated levels of nucleic acids and proteins, which can be used for the development of novel, minimally invasive molecular biomarkers. The purpose of this review is to discuss the commercially available colorectal cancer molecular diagnostic methods as well as to highlight some of the new candidate predictive and prognostic molecular markers for tumor, stool, and blood samples.

A metabolic study on colon cancer using (1)h nuclear magnetic resonance spectroscopy

Background. Colorectal carcinoma is the third cause of cancer deaths in the world. For diagnosis, invasive methods like colonoscopy and sigmoidoscopy are used, and noninvasive screening tests are not very accurate. We decided to study the potential of ¹HNMR spectroscopy with metabolomics and chemometrics as a preliminary noninvasive test. We obtained a distinguishing pattern of metabolites and metabolic pathways between colon cancer patient and normal. Methods. Sera were obtained from confirmed colon cancer patients and the same number of healthy controls. Samples were sent for ¹HNMR spectroscopy and analysis was carried out Chenomex and MATLAB software. Metabolites were identified using Human Metabolic Data Base (HDMB) and the main metabolic cycles were identified using Metaboanalyst software. Results. 15 metabolites were identified such as pyridoxine, orotidine, and taurocholic acid. Main metabolic cycles involved were the bile acid biosynthesis, vitamin B6 metabolism, methane metabolism, and glutathione metabolism. Discussion. The main detected metabolic cycles were also reported earlier in different cancers. Our observations corroborated earlier studies that suggest the importance of lowering serum LCA/DCA and increasing vitamin B6 intake to help prevent colon cancer. This work can be looked upon as a preliminary step in using ¹HNMR analysis as a screening test before invasive procedures.

Risk factors for colonic perforation after screening computed tomographic colonography: a multicentre analysis and review of the literature

BACKGROUND

Computed tomographic (CT) colonography (or 'virtual' colonoscopy) has become an increasingly popular tool for colorectal cancer screening. Colonic perforation, an uncommon complication, is a risk that has not been widely reported.

METHODS

A systematic review of the literature was undertaken to identify all reported risk factors for colonic perforation following CT colonography. In addition, a retrospective multicentre study was undertaken, evaluating all CT colonographies in 10 major metropolitan tertiary referral centres. All colonic perforations were assessed for risk factors.

RESULTS

A range of 'patient'-related and 'procedure'-related risk factors were identified in the literature. Among 3458 CT colonographies, there were two cases of colonic perforation contributing to an incidence of perforation of 0.06%. There was no statistical correlation between the incidence of perforation and institutional experience (P = 0.66). Risk factors common to both cases and the literature included age, recent colonoscopy and manual colonic insufflation. Diverticular disease and recent colonic biopsy were also notable factors.

CONCLUSION

There is a small but real risk of perforation following CT colonography. Patient selection and preventative procedural measures may reduce this risk. The importance of the consent process is emphasized.

Patient satisfaction with colonoscopy: a literature review and pilot study

BACKGROUND

Current guidelines recommend that colonoscopic colorectal cancer screening be undertaken every 10 years after the age of 50 years. However, because the procedure does not meet criteria that promote screening uptake, patient satisfaction with colonoscopy may encourage repeat screening.

OBJECTIVE

To systematically review the literature and conduct a pilot study of patient satisfaction with the colonoscopy experience.

METHODS

All cohort studies from January 1997 to August 2008 in the MEDLINE database that measured either patient satisfaction with colonoscopy, patient willingness to return for colonoscopy under the same conditions or patient preference for colonoscopy compared with other large bowel procedures were identified. The search was supplemented by journal citation lists in the retrieved articles.

RESULTS

Of the 29 studies identified, 15 met the inclusion criteria. Consistently, the vast majority of patients (approximately 95%) were very satisfied with their colonoscopy experience. Patient satisfaction was similar for screening and nonscreening colonoscopy. Patient willingness to return for the procedure ranged from 73% to 100%. Of the five studies that examined modality preference, three studies reported the majority of patients preferred colonography to colonoscopy and two studies reported the reverse. Our pilot study findings mirrored those of other studies that were conducted in the United States. The major limitation of the included studies was that patients who were most dissatisfied may have gone elsewhere to have their colonoscopy.

CONCLUSIONS

Patients were very satisfied with colonoscopy. The majority were willing to return for repeat testing under the same conditions, and colonoscopy was not preferred over other modalities. However, studies were limited by methodological shortcomings.

Computed tomography colonography in acromegaly

INTRODUCTION AND AIM

Acromegalic patients have an increased risk for the development of colorectal cancer. For this reason, since 1996, screening colonoscopy has been recommended in all patients with acromegaly. The aim of our study was to assess the feasibility and to evaluate the results of computed tomography (CT)-colonography in acromegaly.

PATIENTS AND METHODS

We examined 23 acromegalic patients with no history of colorectal cancer (11 females and 12 males; age range 18-79 yr; disease duration range 1-15 yr) with CT-colonography. Twenty of them underwent traditional colonoscopy after the CT-colonography.

RESULTS

CT-colonography examination results were adequate in 17 of 23 cases (73%). CT-colonography found 12 polyps in eight patients, 95% confirmed by traditional colonoscopy. One polyp was a sigmoid cancer, and the diagnosis was confirmed at surgery. There were no polyps found by traditional colonoscopy that CT-colonography was not able to identify. The lesions were located in right colon (two), transversum (three), left colon (five), and sigmoid colon (two). Patient acceptance of the technique was good in 65%, medium in 20%, and poor in 15%.

CONCLUSION

For the first time we have demonstrated that CT-colonography has the potential ability to replace traditional colonoscopy in acromegalic patients. CT-colonography could be used as a screening modality for colon cancer in acromegaly.