Virtual Colonoscopy: Preferred Colorectal Cancer Screening Technique In Average Risk Asymptomatic Adults

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

2. 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

3. 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

4. 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)

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

6. 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

7. 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

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

9. 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

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

11. 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

12. 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

13. 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

14. 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

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