Colonoscopies vs. Stool DNA Tests for Colon Cancer Screening
Posted Nov 19 2009 10:02pm
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.