TalkColonoscopies vs. Stool DNA Tests for Colon Cancer Screening
If you’re 50 years old or older, you’ve been told “Time to get a colonoscopy.” But have you done it? Not exactly the birthday present you’d like, eh?
Everyone should do it, no one wants to, and until now we’ve thought it’s the best way to prevent colon cancer — which is the third most common cancer in the U.S. and the most preventable.
Colonoscopy is the “gold standard” for screening - meaning all the docs say it’s the very best way to detect colon cancer and pre-cancerous polyps. But today’s NY Times has an illuminating article about this:
[A] new study, published today in The New England Journal of Medicine, provides a graphic illustration of how wrong that assumption can be, gastroenterologists say. The study, of 12 highly experienced board-certified gastroenterologists in private practice, found some were 10 times better than others at finding adenomas, the polyps that can turn into cancer. One factor distinguishing the physicians who found many adenomas from those who found few was the amount of time spent examining the colon….
Yet, Dr. Barclay added, “if our group is representative of an average group, you will see people who take 2 or 3 minutes and people who take 20 minutes” to examine a colon. Insurers pay doctors the same no matter how much time they spend. Gastroenterologists say colonoscopies can help prevent colon cancer, but warn that there is a pressing need for better quality control.
The article goes on to cite additional studies that show the accuracy of colonoscopy among physicians varies widely.
Also in the news, Mount Sinai School of Medicine and EXACT Sciences Corporation have announced the results from a prospective, multi-center study of stool DNA testing, which found that the test demonstrated an 88% sensitivity for colorectal cancer, and with equal detection across all stages of cancer, regardless of the cancer’s location in the colon.
What hasn’t made the news is that the medical association that creates screening guidelines has continued to meet about and then put off making guidelines for stool DNA testing. Critics say this is in part because, in a world of increasingly small profits for physicians, doctors make money off performing colonoscopies. And there is no money in writing a lab order for a stool DNA test. I’d love to hear from physicians out there: what is your perspective?
To those critics I would counter that my company has had doctors refer their patients to us for PreGen-Plus, an at-home stool DNA test. (It’s the only one the market right now, as far as I know).
The bottom line is, any screening is better than no screening. The more accurate the screening the better. If you’re going for colonoscopy, make sure you ask your doc about his or her detection rate. If you use any other method, check the accuracy of the test.
Update 12/15/06: This study really has people buzzing. It’s today’s most-emailed NY Times article. Listen to NPR’s coverage.
Update 3/7/08: New colorectal cancer screening guidelines have been issued. The new guidelines include Stool DNA testing, which they refer to as sDNA testing. Here iss the American Cancer Society’s explanation of the new guidelines. Here are the official guidelines for physicians. Bruce asked in a comment (below) where people can get Stool DNA test. You can order one online from my company, DNA Direct, or you can ask your physician if he or she will order the test for you.
Technorati Tags: colon cancer, screening, prevention, colonoscopy, stool dna test, genetic test
Tags: Colon Cancer, colonoscopy, genetic test, prevention, screening, stool dna test
January 3rd, 2007 at 11:16 am
While I applaud advances in screening, who is responsible when the DNA stool test comes back negative and the patient ends up with CRC at some time in the future? Guess who!! The statement “any screening is better than no screening” is inane. How shortsighted and ignorant! A screening test is only as good as a combination of factors which include sensitivity, specificity, the population being screened, prevalence and follow-up. You may not be old enough to remember chest xray screening for TB; it turns out that it provided no benefit. The Mayo Clinic studied collecting sputum samples from smokers; despite detection of cellular changes, screening provided no benefit in terms of treatment or survival. Be honest and put information in its’ proper perspective.
January 29th, 2007 at 2:55 pm
In regards to the above comment by Dr. Peter Balsam about who would be liable should a DNA stool test come back negative with a patient that eventually comes down with CRC, perhaps the good doctor could please tell us who would be liable given the same situation when a Fecal Occult Blood Test (FOBT) fails to accurately detect CRC?
From what I understand, the FOBT is positive in only 30%-50% of the people that have colon cancer. Not a very good track record by any standard of measure.
November 26th, 2007 at 4:13 pm
I think 88% sensitivity is darn good, besides, more than half of the population over 50 does not get tested because they don’t want a camera stuck up there ***. I am sure Peter is just anohter GI that stands to lose money to the DNA based test.
November 27th, 2007 at 10:53 am
Thanks for your comments, Jason and Mike. Indeed, 88% is considered good sensitivity by most medical practitioners. As compared to FOBT, which does have screening guidelines recommended by the American Cancer Society and medical associations, it is clearly an improvement. In fact, other than colonoscopy, DNA Stool testing has the highest sensitivity rate of colorectal cancer screening tests/procedures.
I still stand by my statement, any screening is better than no screening. No screening = no detection of cancer. Screening…well, at least you’ve got a shot at heading it off at the pass. I disagree with the TB screening analogy - different situation, different tests, different sensitivity and specificity, very different outcomes.
November 27th, 2007 at 10:59 am
Let me add one more note here: I’m not a physician, I’m a layperson who reads a lot of literature and whose profession it is to interpret the science to make it accessible and actionable for people and patients. In this blog, I focus on what I think it best for people, regardless of who’s responsible or liable. Dr. Balsam speaks from his experience as a physician, and obviously must address those other issues. But I’ll say this, if there’s adequate informed consent (as there should be for any such test or procedure), then no, the physician’s not liable. By the same token, though, one could ask “who’s liable when a very rare outcome such as a perforated colon occurs as a result of a colonoscopy?”
November 29th, 2007 at 3:41 pm
ACS guidelines - i would be shocked if the SDNA test is not included when new guidelines come out this month. IT would be a crime to humanity to keep this non invasive test off the market to protect GI’s wallet. What Gi’s need to realize is that more colo’s will take place as a result of the sDNA test. REason being, if the 40 million people that do not get tested do, or even small percentage do, it is guaranteed that many will have positive readings for early stage colon cancer. When that happenes, they have to go to a GI to get a colo. So it is a win win for all of us. IT should be in the new guidelines. FOBT is in and it is a very old and inefficient test. thoughts
March 6th, 2008 at 6:22 pm
where caN A PATIENT OBTAIN DNA STOOL TEST?
March 7th, 2008 at 2:02 am
Once again there is confusion between PREVENTING cancer (colonoscopy) and DETECTING it early enough to operate and save a life (fecal tests).
March 7th, 2008 at 1:45 pm
Jason, good news this week! The new ACS guidelines are out, and as you predicted, stool DNA testing (or sDNA) is now included.
This is also good news for people who want stool DNA testing reimbursed by their insurance. Insurance is much more likely to cover testing when it’s included in medical society guidelines.
Gadfly, colonoscopy is a unique procedure in that it can be both a screening test and a preventive procedure: you may go in for a colo to screen, but if the physician sees something while he/she’s in there (polyps), she can remove them at that time. I’m not sure what your point is. Can you clarify?
March 7th, 2008 at 1:47 pm
you can get a DNA test from labcorp. fDNA test is so much better than both FOBT/FIT, it is not even comparable. When the DNA test comes down to $250 per test and taken every 5 years, the cost is almost similar to a FIT test (only detects blood, not cancer, and not all cancers bleed. the ones that do are usually Stage 3 or 4). In other words, average risk folks should switch to the DNA test over annual FIT/FOBT
March 7th, 2008 at 1:50 pm
Lisa!!!!!!!!!!!! great news indeed. I encourage all folks that currently get the FIT/FOBT test to take this fDNA test every five years instead of these stool blood tests. FIT/FOBT only detect blood in the stool, not cancer. Also, not all cancers bleed, so the test is not very sensitivie. On cost, there is a Version 2 test that should hit the market later this year that costs $300 (so about $60 per year over five years), almost as cheap as an annual worthless FIT test costing $40 to $50. The point is this stool DNA test will save countless lives. Great job ACS.
July 2nd, 2008 at 7:13 am
My wife was so afraid of taking the colonostropy that she canceled the appointment. I might add that it has taken tens to build up the courage to make this appoiment.
What to Do?
Frank
July 2nd, 2008 at 1:35 pm
Labcorp will be offering a new stool DNA test in a few months! I would have her call them to get the details! A colo should never be the first screening test in my opinion, it should be used to remove both polyps, precancers and cancer only! It is way to expensive and invasive for a screening tool!