Transanal Endoscopic Microsurg

By Roxanne Nelson
Medscape Medical News

June 26, 2007 — Transanal excision (TA) is the most common method of surgically excising local rectal lesions, but data presented at the annual meeting of the American Society of Colon and Rectal Surgeons, in St. Louis, Missouri, suggests that transanal endoscopic microsurgery (TEM) may offer certain advantages over the more standard procedure. In a study that compared TA with TEM, results showed that TEM was the technique of choice for excising local rectal neoplasms.

While still relatively uncommon in the United States, TEM has been used for more than 2 decades in Europe and was pioneered in Germany by Gerhard Buess, MD, from the University of Tübingen. In the United States, there are less than 100 facilities that perform the procedure, according to senior investigator Peter Cataldo, MD, and less than 10 that excise a significant number of lesions using TEM. The largest number of TEM procedures performed in the United States is at the University of Vermont, in Burlington, where Dr. Cataldo is an associate professor of surgery.

TEM is a minimally invasive approach that provides magnified vision and superior optics for removing tumors throughout the entire rectum, explained Dr. Cataldo. But while it is starting to become more popular, the technique has been slow to catch on.

"There are 3 primary reasons for that," Dr. Cataldo told Medscape. "There are not many facilities that see enough patients who are candidates for the procedure. The second reason is that it is a difficult technique to learn. And third, the equipment is expensive."

Thus far, there have been no large clinical trials comparing the efficacy of TEM with TA. In this retrospective study, the researchers compared TEM with TA for both benign and malignant rectal masses. The cohort encompassed 171 patients who underwent either TA or TEM (82 patients TEM, 89 TA) for adenocarcinoma or polyps between 1990 and 2006. Both patient groups were similar in demographics such as age, sex, and lesion type, stage, and size, with a mean follow-up of 34 months.

The TEM procedure was much more likely to result in a complete resection and yield negative margins, as compared with TA (88% vs 71%). This was true whether the lesion was benign or malignant. It was also more likely to produce an intact, nonfragmented specimen, as compared with TA (94% vs 63%).

"With TEM it almost always comes out as an intact specimen, and that makes it much easier for the pathologist to evaluate," said Dr. Cataldo.

The rate of recurrence, both local and distant, was also lower in patients who had undergone TEM, as compared with TA (5% vs 25%). This was particularly true for rates of local recurrence, which were significantly lower for both benign and malignant lesions following TEM (4% vs 20%). The rate of complications was similar between both groups.

The lower rates of recurrence and better overall survival are probably due to the fact that TEM allows for a more precise tumor resection, explained Dr. Cataldo.

"Overall, rectal access is vastly superior with transanal endoscopic microsurgery, because you can visualize the entire rectum," said Dr. Cataldo. "The visualization is superior to transanal excision, and these attributes translate into a much more precise incision enclosure of the rectal masses."

One drawback of the procedure is the cost of the equipment needed to perform TEM. While the TA procedure can be performed with standard surgical instruments, the cost of TEM equipment ranges from $60,000 to $80,000. Aside from the associated expense of the equipment, the learning curve is steep, explained Dr. Cataldo. It is essential, therefore, that surgeons have an adequate number of cases to develop and maintain expertise in this technique.

"But once you've mastered it, the procedure is not terribly difficult to perform and takes about an hour to an hour and 15 minutes to perform," he said. "But most important, in many patients, you can avoid the need for an abdominal operation and possibly the need for a colostomy in some circumstances."

Annual meeting of the American Society Colon and Rectal Surgeons: Abstract GSF1. Presented June 5, 2007.