What does endoscopic biopsy surveillance inBarrett's esophagus involve?
Periodic random biopsies
In established Barrett's esophagus,endoscopic surveillance is done at periodic intervals to look for dysplasia. Atthe time of endoscopy, many biopsies are taken of the Barrett's mucosa. Therecommended approach is to do four mucosal biopsies (one in each quadrant ofthe circumference of the esophagus) at the junction of the stomach andesophagus, and four more biopsies (again, one in each quadrant) should berepeated every two centimeters (about 3/4 inch) proximally until the length ofthe Barrett's has been completely biiopsied. If available, a large forceps (theso-called jumbo forceps) is desirable to procure biopsy specimens.四川省第四人民医院消化内科常玉英
The current trend is to increase thesurveillance intervals in patients who do not have dysplasia. For example, theapproach may be to do the surveillance biopsies initially and then a yearlater. If no dysplasia is found, the surveillance can be done every threeyears. Other doctors would do it every two years. The bottom line forendoscopists doing surveillance, however, is: "Do it right so we can do itless often." There is some evidence showing that patients with cancersfound during the course of surveillance have a better survival rate than thosewho come to the doctor because of cancer symptoms without any previoussurveillance. The ultimate proof that surveillance works, however, will beobtained only when surveillance is applied to a large population at risk andnot just to those who seek medical attention. The same issues pertain to othercancer screening tests (such as, mammography and prostate cancer screening). Ifcancers are found in Barrett's patients under surveillance, the 5-year survivalrate is at least 80%. This means that at least 80% of the cancer patients wouldbe alive 5 years after treatment. The problem is that only 5% of patients whoundergo surgery for esophageal adenocarcinoma had been diagnosed with Barrett'sesophagus preoperatively. Thus, only the 5% with known Barrett's were eligiblefor surveillance before their surgery. In other words, the challenge is not todo more surveillance, but to conduct more screening to identify those who haveBarrett's esophagus in the population with chronic GERD.
Other ways to diagnose dysplasia
There is great interest in developingtechniques that would use targeted, rather than random biopsies in identifyingareas of dysplasia or early cancer. Dysplasia often is endoscopicallyinvisible, which means that it can't be seen just by looking at the esophageallining through the endoscope. So, different optical enhancing techniques arebeing evaluated. The idea is to highlight the areas of dysplasia so thattargeted biopsies can be obtained. These optical methods include the use of dyesprays (chromoendoscopy), spectrophotometry to measure light wave intensity,and a technique called optical coherence tomography. These procedures, however,remain experimental at present.