Computed tomographic colonography: Hope or hype?

A Review on Emerging Techniques for Diagnosis of Colorectal Cancer

Common detection methods in practice for diagnosing colorectal cancer (CRC) are painful and invasive leading to less participation of individuals for CRC diagnosis. Whereas, improved or enhanced imaging systems and other minimally invasive techniques with shorter detection times deliver greater detail and less discomfort in individuals. Thus, this review is a summary of the diagnostic tests, ranging from the simple potential use in developing a flexible CRC treatment to the patient's potential benefits in receiving less invasive procedures and the advanced treatments that might provide a better assessment for the diagnosis of CRC and reduce the mortality related to CRC.

Methylation Status of Corticotropin-Releasing Factor (CRF) Receptor Genes in Colorectal Cancer

The corticotropin-releasing factor (CRF) system has been strongly associated with gastrointestinal pathophysiology, including colorectal cancer (CRC). We previously showed that altered expression of CRF receptors (CRFRs) in the colon critically affects CRC progression and aggressiveness through regulation of colonic inflammation. Here, we aimed to assess the potential of CRFR methylation levels as putative biomarkers in CRC. In silico methylation analysis of CRF receptor 1 (CRFR1) and CRF receptor 2 (CRFR2) was performed using methylome data derived by CRC and Crohn's disease (CD) tissues and CRC-derived circulating cell-free DNAs (ccfDNAs). In total, 32 and 33 differentially methylated sites of CpGs (DMCs) emerged in CRFR1 and CRFR2, respectively, between healthy and diseased tissues. The methylation patterns were verified in patient-derived ccfDNA samples by qMSP and associated with clinicopathological characteristics. An automated machine learning (AutoML) technology was applied to ccfDNA samples for classification analysis. In silico analysis revealed increased methylation of both CRFRs in CRC tissue and ccfDNA-derived datasets. CRFR1 hypermethylation was also noticed in gene body DMCs of CD patients. CRFR1 hypermethylation was further validated in CRC adjuvant-derived ccfDNA samples, whereas CRFR1 hypomethylation, observed in metastasis-derived ccfDNAs, was correlated to disease aggressiveness and adverse prognostic characteristics. AutoML analysis based on CRFRs methylation status revealed a three-feature high-performing biosignature for CRC diagnosis with an estimated AUC of 0.929. Monitoring of CRFRs methylation-based signature in CRC tissues and ccfDNAs may be of high diagnostic and prognostic significance in CRC.

Colorectal cancer screening: An updated review of the available options

Colorectal cancer (CRC) is a significant cause of morbidity and mortality worldwide. However, colon cancer incidence and mortality is declining over the past decade owing to adoption of effective screening programs. Nevertheless, in some parts of the world, CRC incidence and mortality remain on the rise, likely due to factors including “westernized” diet, lifestyle, and lack of health-care infrastructure and resources. Participation and adherence to different national screening programs remain obstacles limiting the achievement of screening goals. Different modalities are available ranging from stool based tests to radiology and endoscopy with varying sensitivity and specificity. However, the availability of these tests is limited to areas with high economic resources. Recently, FDA approved a blood-based test (Epi procolon^®) for CRC screening. This blood based test may serve to increase the participation and adherence rates. Hence, leading to increase in colon cancer detection and prevention. This article will discuss various CRC screening tests with a particular focus on the data regarding the new approved blood test. Finally, we will propose an algorithm for a simple cost-effective CRC screening program.

CT colonography in the diagnosis and management of colorectal cancer: Emphasis on pre- and post-surgical evaluation

This article addresses the use of computed tomographic colonography (CTC) for the diagnosis and management of colorectal cancer, focusing on presurgical evaluation of the colon proximal to an occlusive cancer and surveillance after cancer resection surgery. The key evidences accumulated in the literature and future work needed are summarized. CTC is a technically robust and the most practical method to evaluate the colon proximal to an occlusive cancer, which prevents colonoscopic examination past the occlusion, either before or after metallic stent placement. The high sensitivity of CTC for detecting cancers and advanced adenomas in the proximal colon can help prevent additional surgical procedures in patients showing negative results. However, the accuracy of CTC for distinguishing intramural cancers from adenomas is low, and the technique is limited in guiding management when a medium-sized lesion that do not show invasive features such as pericolic extension or nodal metastasis is found in the proximal colon. A maximal diameter ≥ 15 mm has been proposed as a criterion for surgical removal of proximal lesions. However, this needs to be verified in a larger cohort. In addition, the influence of presurgical CTC results on the current post-cancer resection colonic surveillance timeline remains to be determined. CTC can be readily added to the routine abdominopelvic CT in the form of contrast-enhanced CTC, which can serve as an effective stand-alone tool for post-cancer resection surveillance of both the colorectum and extracolonic organs. Although the accuracy of CTC has been demonstrated, its role in the current colonoscopy-based postoperative colonic surveillance protocols remains to be determined. Readers of CTC also need to be knowledgeable on the colonic lesions that are unique to the postoperative colon.

Cancer prevention health services research: an emerging field

In October 2009, The University of Texas MD Anderson Cancer Center hosted a symposium, "Future Directions in Cancer Prevention and Control: Workforce Implications for Training, Practice, and Policy." This article summarizes discussions and an Internet and literature review by the symposium's Health Services Infrastructure Working Group. We agree on the need for the recognition of Cancer Prevention Health Services Research (CP-HSR) as a unified research field. With advances in cancer screening and increased emphasis on preventive services under healthcare reform, there is a growing need for investigators with both cancer prevention and HSR expertise to consider the comparative effectiveness of cancer screening methods, the cost-effectiveness of early detection technologies, and the accessibility of preventive care for individuals at risk of cancer. Defining CP-HSR as a field will provide investigators with credibility and will serve to draw more researchers to the field. Increasing funding to train individuals in CP-HSR will be important to help meet the anticipated demand for investigators with this specialized multidisciplinary expertise.

Colorectal cancer screening: update for 2011

Colorectal cancer is the third most common cancer in the United States. Although mortality and incidence rates are declining in the United States, colorectal cancer screening remains underused. In addition, recent data suggest that colonoscopy, which is often considered the gold standard for colorectal cancer screening, is less protective for right-sided tumors, which are more likely to be flat or depressed and are more affected by an inadequate bowel preparation. Imaging technologies such as chromoendoscopy and narrow band imaging have been developed to improve delineation of suspicious lesions during colonoscopy. In addition, other new modalities such as computed tomography colonography (CTC), capsule endoscopy, fecal immunochemical tests, and fecal DNA tests may offer less invasive screening options for patients who decline colonoscopy.

Preferable colonic investigations for isolated abdominal pain

OBJECTIVES

Isolated abdominal pain is seen as a poor indication for colonic investigations. The yield of serious pathology detected by optical colonoscopy (OC) has differed greatly in published series. This study aims to establish the yield of colonic investigations for isolated abdominal pain.

METHODS

A retrospective analysis of the endoscopy database was undertaken on all OCs performed from 2000 to 2008. The yield of OCs for detection of pathology (polyps, cancers, and inflammatory bowel disease) was compared for the symptoms of abdominal pain, chronic diarrhea, or anemia. Data on computed tomographic colonographies (CTC), performed for isolated abdominal pain in 2008, were used to compare the yield of CTCs and OCs.

RESULTS

Of the 8564 OCs and 525 CTCs performed, 5.4% and 8.2% were undertaken for isolated abdominal pain, respectively. The yield of OCs for overall pathology detection was not significantly different for abdominal pain (23.87%), compared to other indications (20.34-24.85%). The yield of pathology detection was not significantly different for CTC (20.93%) and OC. Colonic polyps were the most common pathology (OC 16.05%, CTC 18.6%).

CONCLUSION

Colonic investigations undertaken for isolated abdominal pain had a high yield of incidental colonic pathology. The detection of polyps could be beneficial, but it does not explain the symptoms. CTC offers a less invasive way of detecting colonic pathology in such patients, while maintaining the same yield. If CTC is used as a first line of investigation, it could spare 75% of patients the colonoscopy procedure.

Computed tomographic colonography

This article provides basic information about computed tomographic colonography (CTC) and reviews the preparation, methods, and tools required for the procedure. The clinical uses for CTC (screening/diagnosis of colon cancer and colonic obstruction) are outlined, and its accuracy and validity are compared with other diagnostic methods. A summary of the benefits and risks of the test are presented and the current practicalities for implementation are addressed.