he following post was contributed by Mark E. Klein, MD, FACR, member of the ACR Colon Cancer Committee.
In April of 2013, I was due for repeat colorectal cancer (CRC) screening. I had undergone an optical colonoscopy in my late 40s, but it had been over 10 years since that exam. Instead of another optical colonoscopy (OC), I chose to have a Virtual Colonoscopy (VC), also known as CT Colonography (CTC).
Some of you reading this piece might be unfamiliar with VC, and that wouldn’t be a surprise. VC is the best-kept medical secret in the United States. VC substitutes ultra-low dose CT scans for the invasiveness of a typical optical colonoscopy. Here are just a few of the advantages of VC over OC:
- VC is completely safe. There is almost zero risk of perforation when automated CO2 insufflation is utilized. Contrast this with the uncommon but very real risk of colon perforation with OC. A screening test should be as safe as possible; no one should ever be seriously injured or die from a screening study. Morbidity and mortality can and do result from OC.
- No anesthesia is required for VC. Therefore, there is no loss of a day’s work (or a day’s play). Also no one need accompany the patient to the procedure.
- Other abnormalities of the abdomen and pelvis can be revealed. After all, even though it is low-dose, it is still a CT exam.
This last bullet point returns us to the story of my VC on that day in April 2013. My colon was perfect, not a polyp to be found. But on review of the standard CT images, I did notice an abnormal contour of my left kidney. An MRI confirmed a solid enhancing 3 cm left renal mass. Three months later following robotic partial nephrectomy my papillary renal cell carcinoma was in a jar. (I memorialized the wild story of my surgical adventure here.)
Here is what else you should know.
- VC is at least as accurate as OC for the detection of significant polyps. VC does slightly better than OC for 10 mm or greater polyps, and it is equivalent to OC for 6-9 mm polyps. Only for the most diminutive — and inconsequential — sub-6mm polyps is OC more sensitive than VC.
- VC is better than OC when it comes to detecting actual CRC, especially on the right side of the colon.
- More noncolon cancers are found with VC — 1 in 300 patients — than CRC — 1 in 500 patients. Overall some form of CA is found in about 1 in 200 patients scanned. Detection of unsuspected aortic aneurysms and CT bone densitometry are additional free benefits of VC screening.
- Radiation doses are currently very low, on the order of background radiation, 3 mSv or less for the complete exam.
- Several studies have documented that patients prefer VC to OC.
- What we have then is a screening test that is at least as accurate for the detection of polyps, the precursor lesion of CRC, as optical colonoscopy. It can even detect so-called flat polyps as well if not better than OC. VC is safe, requires no sedation or time off work, and as an extra benefit can detect significant disease outside of the colon. As if that wasn’t sufficient, VC costs far less than OC.
VC is better, safer and less expensive than OC. It should be the screening test of choice for colorectal cancer prevention in the United States and worldwide.
Want to really make a difference in your career? Embrace this life-saving exam. Learn it, and make sure your colleagues, friends, family and others know that VC is an American Cancer Society-recommended CRC screening option. As I discovered, the life you save may be your own.
Pickhardt PJ. CT colonography for population screening: ready for prime time? Dig Dis Sci 2015;60:647-659.
Johnson CD, Chen MH, Toledano AY, et al. Accuracy of CT colonography for detection of large adenomas and cancers. N Engl J Med 2008;359:1207-17.
Kim DH, Pickhardt PJ, Taylor AJ, et al. CT colonography versus colonoscopy for the detection of advanced neoplasia. N Engl JMed. 2007;357:1403-1412.
Pooler BD, Baumel MJ, Cash BD, et al. Screening CT colonography: multicenter survey of patient experience, preference, and potential impact on adherence. Am J Roentgenol. 2012;198:1361-1366.
Pickhardt PJ, Hassan C, Halligan S, Marmo R. Cancer: CT Colonography and Colonoscopy for Detection—Systematic Review and Meta-Analysis. Radiology 2011;259;393-405.