A study published in today’s JAMA comparing CT scan to colonoscopy for detection of colon polyps and cancer in high risk individuals found that CT scan slightly underperformed colonoscopy, especially in folks with GI bleeding. But overall it did pretty well.
Of 1103 participants, 937 were included in the final analysis: 373 cases in the family-history group, 343 in the group with personal history of adenomas, and 221 in the FOBT-positive group. Overall, CT colonography identified 151 of 177 participants with advanced neoplasia 6 mm or larger (sensitivity, 85.3%; 95% confidence interval [CI], 79.0%-90.0%) and correctly classified results as negative for 667 of 760 participants without such lesions (specificity, 87.8%; 95% CI, 85.2%-90.0%). The positive and negative predictive values were 61.9% (95% CI, 55.4%-68.0%) and 96.3% (95% CI, 94.6%-97.5%), respectively; after group stratification, a significantly lower negative predictive value was found for the FOBT-positive group (84.9%; 95% CI, 76.2%-91.3%; P < .001).
In an accompanying editorial it was suggested that the slightly lower rate of cancer detection with CT may be more acceptable to folks who have to have repeated studies because of high risk (with the multiple studies making up for the decreased detection rate of an individual study), and especially for those high risk patients who would choose to have nothing rather than undergo the colonoscopy.
With the majority of individuals in the United States who meet criteria for colorectal cancer screening and surveillance not undergoing recommended procedures, an imperfect test that has a lower risk profile and greater acceptance among patients seems to be an appealing solution.
In other words, if it’s a choice between nothing and a CT scan, the CT scan is reasonable. But the colonoscopy is better.
Although I am not a gastroenterologist, I did have a colonoscopy last week. The prep was one of the more difficult things I’ve done, but the procedure itself was nothing. I’ll probably have to have another in 3-5 years due to family history, and will choose the prep and colonoscopy over a CT anytime.
Virtual CT requires an enema. Not sure why this is preferred over the bowel prep. 99% of my patients say that the procedure is nothing; the prep is the bad part.
Dr Rob – Not to mention, don't you have to drink that horrible tasting stuff for the CT too?
I asked my GI doc, and he agreed to provide me with, a scrip for the pills to take instead of the stuff to drink. I sat up all the glasses of liquids across the kitchen table and set the timer and followed the instructions to a T.
It was unpleasant, but heck compared to a migraine, endometriosis pain before I was diagnosed and given adequate painkillers, and a reaction I had to codeine it was not a big deal.
It amazes me that there are people in this country who die from colon cancer because they don't want to get a colonoscopy.
It really helps to do two days of a diet heavy on the veg & fruit, no beef or pork, some chicken or fish or eggs. Then the day before just the clear liquids. You'll be hungry. The new prep kits are not nearly as bad as the old ones and normally no pre-test enema is required. What they often fail to explain is that the rapid intake of either water or halflyte pushes everything through the intestines within about 2 hours. Understanding WHY makes it easier to gag down all that liquid. Having it cold, using a straw, and if you feel nauseated put a little salt on your tongue. Good for you getting the test. I've been nagging my husband for a year about getting the exam.