Virtual Colonoscopy: Preferred Colorectal Cancer Screening Technique In Average Risk Asymptomatic Adults By: Katy Carroll Advisor: David Fahringer March 8, 2007 PAS 646

Why Screen?  Best method for controlling colorectal cancer  70-75% of CRC occurs in asymptomatic individuals  Detect and remove adenomatous polyps, precursor lesions for CRC, and detection of early stage carcinoma  Reduce mortality

Barriers to Screening  Race  Lack of health care coverage  Low education levels  Fear of pain  Fear of complications during procedure  Embarrassment of preparation process  Morbidly obese adults  Cost issues  Lost time from work  Lack of access  Sex of endoscopist

Risk factors for CRC  Family history of colorectal cancer  Personal history of adenomas or ovarian/uterine cancer  Long standing IBD (8-15 years)  Environmental factors (diet and meds)  Lifestyle factors (physical inactivity, obesity, and cigarette smoking)

Incidence & Mortality  Second most common cancer in United States  Second leading cause of cancer related death in the USA

Why Discrepancies?  35% of CRCs diagnosed at localized stage in African Americans compared to 39% in Caucasians  Possibly due to hormone and NSAID use  Less utilization of current screening methods

Pathophysiology  Current belief is that most CRCs stem from preexisting adenomas  Adenomas that are large and/or have a villous component determine likelihood of containing invasive carcinoma  Polyps are slow growing and must grow for five years before they are clinically significant  Normal colonic mucosa is transformed into benign adenoma, followed by progression to polyp containing cancer, which can become invasive

Methods for Screening  Colonoscopy  Flexible sigmoidoscopy  Air contrast barium enema  Fecal occult blood test (FOBT)  CT colonoscopy

Detection Rates  Colonoscopy: Sensitivity of 88.2 (>10mm) Sensitivity of 90.0 (<6mm)  CT colonoscopy: Sensitivity of 92.2 (>10mm) Sensitivity of 85.7 (<6mm)  FOBT: detected 23.9% of advanced neoplasia  Flex Sig: 76% when used with FOBT  Air contrast barium enema: failed to identify up to 50% of polyps greater than 10mm in diameter

Cost  Screening with any method is more cost effective than treating/intervening when compared with no screening

Virtual vs. Optical Colonoscopy  Patients reported less discomfort with virtual colonoscopy  Shorter examination time with VC  VC less embarrassing  72.3% of patients preferred VC as screening technique compared to 5% preferred CC as screening technique  More patients were willing to repeat a VC at shorter intervals than CC

Remove Barriers  Study by Pickhardt et al. showed that when CT colonoscopy was covered by third party payers, patient demand for procedure rapidly increased.  Third party reimbursement for virtual colonoscopy has the potential to make a significant impact on patient compliance with CRC screening guidelines.  Fear of pain

Conclusion  Not screening for CRC has great cost measured in dollars and lives  Very high detection rates in people with polyps over 5mm  Low detection rates for polyps less than 5mm could be acceptable because majority of polyps this size do not progress to CRC  Studies underway concerning technology advances that can affect the sensitivity and specificity for polyps and malignancy

Conclusion (Cont.)  If optical and virtual colonoscopy were covered equally on insurance plans more people would be compliant with CRC screening guidelines- as in Pickhardt’s study  Less time for actual procedure saves screening sites money  U.S. government would save money in the long run due to reduced Medicare/Medicaid money being spent on treatment/intervention  Studies with stool tagging and digital subtraction are going on to eliminate bowel preparation, which would increase patient acceptance

References  American Cancer Society. Cancer facts and figures for African Americans Available at: Accessed November 29,  Bosworth HB, Rockey DC, Paulson EK, Niedzwiecki D, Davis W, Sanders LL, et al. Prospective comparison of patient experience with colon imaging tests. The American Journal of Medicine. 2006; 119:  Dale DC, Federman DD, editors. ACP medicine edition. New York: WebMD; p  Fischbach FT, Dunning MB. A manual of laboratory and diagnostic tests. 7 th edition. Philadelphia: Lippincott Williams & Wilkins;  Gluecker TM, Johnson CD, Harmsen WS, Offord KP, Harris AM, Wilson LA, et al. Colorectal cancer screening with CT colonography, colonoscopy, and double-contrast barium enema examination: prospective assessment of patient perceptions and preferences. Radiology. 2003; 227:  Huang CS, Lal SK, Farraye FA. Colorectal cancer screening in average risk individuals. Cancer Causes and Control. 2005;16:  Kentucky Cancer Registry. Cancer incidence and mortality rates in Kentucky. Available at: Accessed November 29,  Lexington Diagnostic Center. Virtual colonoscopy. Available at: Accessed November 28,  National Cancer Institute. Cancer stat fact sheets. Available at: Accessed November 29,  Nicholson FB, Taylor S, Halligan S, Kamm MA. Recent developments in CT colonography. Clinical Radiology. 2005; 60:1-7.  Pickhardt PJ, Choi JR, Hwang I, Butler JA, Puckett ML, Hildebrandt HA, et al. Computed tomographic virtual colonoscopy to screen for colorectal neoplasia in asymptomatic adults. The New England Journal of Medicine. 2003; 349:  Pickhardt PJ, Taylor AJ, Kim DH, Reichelderfer M, Gopal DV, Pfau PR. Screening for colorectal neoplasia with CT colonography: initial experience from the 1 st year of coverage by third-party payers. Radiology. 2006; 241:  Ristvedt SL, McFarland EG, Weinstock LB, Thyssen EP. Patient preferences for CT colonography, conventional colonoscopy, and bowel preparation. The American Journal of Gastroenterology. 2003; 98:  Saliangas K. Screening for colorectal cancer. Tech Coloproctol. 2004; 8:S10-S13.  Segnan N, Senore C, Andreoni B, Arrigoni A, Bisanti L, Cardelli A, et al. Randomized trial of different screening strategies for colorectal cancer: patient response and detection rates. Journal of the National Cancer Institute. 2005; 97:  WebMD. Colorectal cancer health center. Available at: Accessed February 26,