Colorectal cancer colonoscopy

A case-control study was designed to explore risk factors for colorectal adenomas. Adenomas are precursors to 80-90% of all colorectal cancers. The study used 236 cases (with adenomas or polyps) and 409 controls (no adenomas) (Tseng ef aF., 1996) (Tabic 11,2). All subjects were patients receiving colonoscopy exams. The subjects were not recruited from the general public, A month or so after the exam, the subjects were asked to fill out a food choice questionnaire. 

Colorectal cancer or adenomatous polyps in first-degree relative younger than 60 years or in two or more first-degree relatives at any ages High risk Colonoscopy" Age 40 or 10 years before the youngest case in family, whichever is earlier Every 5-10 years... 

For these and other reasons (i.e., obviously hydrocolonic sonography does not offer the possibility/ opportunity to collect biopsies or remove polyps), although less invasive and expensive than colonoscopy, the use of hydrocolonic sonography, as a screening tool for colorectal cancer, should be evaluated with due care. 

Van Gelder RE, Nio CY, Florie J et al (2004b) Computed tomographic colonography compared with colonoscopy in patients at increased risk for colorectal cancer. Gastroenterology 127 41-48... 

Prentice RL, Thomson CA, Caan B et al. (2007) Low-fat dietary pattern and cancer incidence in the Women s Health Initiative Dietary Modification Randomized Controlled Trial. J Natl Cancer Inst 99 1534 1543 Purkayastha S, Tekkis PP, Athanasiou T et al. (2005) Magnetic resonance colonography versus colonoscopy as a diagnostic investigation for colorectal cancer a meta-analysis. Clin Radiol 60 980 989... 

Fenlon HM (2002) CT colonography pitfalls and interpretation. Abdominal Imaging 27(3) 284-291 Fenlon HM, Nunes DP, Schroy PC et al. (1999) Comparison of virtual and conventional colonoscopy for the detection of colorectal polyps. N Engl J Med 341(20) 1496-1503 Ferruci JT (2000) CT colonography for colorectal cancer lessons from mammography. Am J Roentgenol 174(6) 1539-1541... 

The indications for CTC closely follow the indications for conventional optical colonoscopy with few exceptions. These indications include screening asymptomatic high- and average-risk patient populations, pre-operative assessment of the colon proximal to an obstructing mass, evaluation of patients with change in bowel habits, surveillance of patients post colorectal cancer surgery, and incomplete or failed colonoscopy. Patients with bleeding diathesis, contraindications to sedation, and frail and elderly patients may also be better suited for CTC than conventional colonoscopy. 

A landmark multicenter study published by Pickhardt et al. compared CT colonography and conventional colonoscopy in asymptomatic average-risk patient population. As a screening study, comparable adenoma and colorectal cancer detection rates were reported (Pickhardt et al. 2003). In... 

A subset of patients, including the elderly, those with cardiovascular disease, bleeding diathesis and a history of failed colonoscopies, are better suited to undergo CTC for colorectal cancer screening compared to colonoscopy or DCBE. 

The American Society of Clinical Oncology developed in 1999 a set of guidelines for the surveillance of the post-operative patient with colorectal cancer after thorough review of the literature of common surveillance protocols. Protocols were reviewed on the basis of reduction in morbidity and five-year disease free survival. Monitoring carcino-embryonic antigen (CEA) levels and colonoscopy were found to be the most effective in many protocols, with liver function evaluation, fecal occult blood testing, liver ultrasound and chest X-ray being less effective in overall outcome (Desch et al. 1999). Colonoscopy appears to have the best predictive value for morbidity. A pre-operative or peri-operative evaluation of the entire colon is essential in the surveillance... 

Pregnancy is a relative contraindication to CTC. The radiation dose and absorbed dose to the fetus during the dual scan is the major issue. In these rare instances that a pregnant patient is suspected to have a colorectal cancer, there is a real risk of perforation with conventional colonoscopy and CTC... 

Virtual colonoscopy, now ten years old, has made substantial progress in the detection of adenomas and colorectal cancer. Recent studies report comparable sensitivities and specificities to conventional colonoscopy for polyps 10 mm or larger on a per polyp basis. CTC is currently approved by Medicare as a diagnostic study in patients with positive symptoms and after failed colonoscopy. Work continues to approve CTC as a colorectal cancer screening exam. Many experts believe CTC is also ready to be adopted into the colorectal screening algorithm. 

Morrin MM, Farrell RJ, Kruskal JB et al. (1999) Virtual colonoscopy a kinder, gentler colorectal cancer screening test Lancet 354 1048-1049... 

Bowles CJ, Leicester R, Romaya C et al. (2004) A prospective study of colonoscopy practice in the UK today are we adequately prepared for national colorectal cancer screening tomorrow Gut 53 277-283... 

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