Fewer colonoscopies and biopsies to come…

| October 22, 2008

There are a number of clinical investigators exploring the use of non-invasive or minimally invasive technologies to scree for colon cancer that I have posted about in the past.  Another study has been published from here looking at DNA in stool samples recently presented at a large national meeting and published in the medical literature.  A summary is below. 

Other investigators have reported success with light scattering techniques in the colon using nothing more invasive than an endoscopy device analagous to a rectal thermometer.  These investigators have reported being able to detect "field effect"  of pre-malignant areas of the colon based on the spectral patterns they have observed in conjunction with traditional colonoscopy. 

While widespread clinical utility may be years off for pathologists in nearly all practice settings, these types of specimens represent a high volume of routine surgical pathology practice.  I wonder what impact some of these technologies will have on biopsy volume down the road. 

As with any test, there will be imperfect sensitivity and specificity with false positives and false negatives necessitating other testing.  We are seeing this as well with companies and laboratories offering genetic testing as a screening tool.  There is tremendous interest in earlier detection of common cancers where stage (extent of disease at time of diagnosis) dictates treatment and prognosis I wonder if some of these screening tests may actually result in more procedures negating their effectiveness. 

Perhaps then patients will go for virtual colonoscopy, then traditional colonscopy and biopsy….

HealthDay (10/8, Mozes) reported that researchers at the Mayo Clinic in Rochester have developed SDT-2, a "new and improved DNA stool sample test, to screen for colon cancer," and it "is twice as effective at catching cancer and serious precancerous polyps than either current blood stool sample tests or an older version of DNA testing." Lead investigator David A. Ahlquist, M.D., explained that using "blood as a marker for colon cancer has limitations," because the majority of "polyps basically don’t bleed." All precancerous polyps, however, "shed cells that contain abnormal DNA," meaning that "a stool-based DNA test is a strategically more rational approach." According to the paper appearing in the Oct. 7 issue of the Annals of Internal Medicine, "3,800 healthy adults" were subjected to testing. Samples collected by the participants were analyzed using "three different screening methods." The "best blood testing was able to detect 21 percent of actual cancer cases," while the "older SDT-1 DNA test" detected "20 percent of cancer cases." But the "newer SDT-2 DNA test was found to be much more effective — detecting 40 percent of cancer cases and serious polyp growth."

Category: Clinical Laboratories

Comments (3)

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  1. EM says:

    Less biopsies of normal colon, maybe, but more polyps will be excised and need to be examined.

  2. Great wealth of info! Thanks for the post. I really do agree with the clinical investigators on the use of minially invasive technologies. Patients comfort must be the the top priority for any development.

  3. Virtual colonoscopy, although it’s non-invasive, carries no risk of invasive punctures nor the risks of general anesthesia carries radiation induced cancer risks since a CT scan is required. In addition, once the scan is complete, if anything suspicious is noted, a full colonoscopy would be needed for biopsy taking. These genetic tests are an excellent way to do a pre-scanning without the radiation.