By Kimberly McGhee
Transanal total mesorectal excision (TaTME) has garnered a great deal of attention and created much excitement in the field of rectal surgery because it represents a reversal of perspective—literally—about how best to excise tumors and the surrounding mesorectal envelope in the lower third of the rectum. Unlike traditional TME, which involves introduction of a laparoscopic camera and specialized laparoscopic tools through small slits in the abdomen to excise these tumors from above, TaTME reverses the process and introduces these tools via a multichannel port in the anus so that the tumor can be visualized and removed from below.
For even experienced colorectal surgeons, excision of tumors in the lower third of the rectum by either open or conventional laparoscopic methods is extremely challenging, particularly in obese patients; in male patients, who have a narrow pelvis; and in patients whose anatomy has been altered by previous radiotherapy. This is due in part to the difficulty of navigating the narrow and curved pelvic space with a rigid laparoscope. By approaching from below, TaTME solves the problem of access.
George, who assumed leadership of the Section of Colon and Rectal Surgery in late 2015, has received specialized training in TaTME and has successfully performed 18 of these procedures, three of them at MUSC Health. A full spectrum of minimally invasive surgeries (MIS) for colorectal cancer, including laparoscopic, robotic, and transanal techniques, are now offered by MUSC Health. Indeed, more than 90% of patients opt for MIS, which require much smaller incisions than open surgery, reducing recovery time and pain for the patient.
TaTME is a hybrid approach in which both traditional abdominal laparoscopy and transanal laparoscopy are used to remove a rectal tumor along with its intact mesorectal envelope.1 Traditional laparoscopy is used to mobilize the descending and sigmoid colon and the splenic flexure, and then the transanal approach is used for the dissection and excision of the mesorectal “packet” containing the tumor. The “packet” is typically removed via the anus but, for bulky tumors, a small exit incision can be made in the abdomen. The colon and remaining anus can then be sewn or stapled together to restore continuous intestinal flow (i.e., anastomosis), enabling the patient to defecate normally instead of having to rely on a stoma (i.e., an opening from the colon to the surface of the skin).
Before TaTME, abdominoperineal resection (APR), in which the sigmoid colon, rectum, and anus are removed and a stoma is created through which the patient can void bodily waste, was considered the gold standard for excising tumors in the lower third of the rectum. In addition to preserving sphincter function, TaTME offers several other key advantages over APR performed as an open surgery, including a shorter and less painful recovery and a reduced likelihood of complications such as infections, hernias, impotence, and urinary incontinence.
The first TaTME was performed in 2009 by Antonio M. Lacy, M.D., Ph.D., at the Hospital Clinic of Barcelona in Spain. In a study of a cohort of 140 patients undergoing TaTME, published in 2015 in the Journal of the American College of Surgeons, Lacy and his group report shorter surgical times and very satisfactory conversion (to open procedure) and complication rates for TaTME compared with traditional TME, as well as equally good oncologic outcomes and excellent specimen quality (i.e., intact mesorectal envelope), an important prognostic factor.2 In a separate article comparing TaTME with traditional laparoscopy, Lacy and colleagues showed that successful coloanal anastomosis was more likely and that the rate of early readmissions was reduced with TaTME.3 Only colorectal surgeons who have received the appropriate training and who have extensive experience with laparoscopic techniques should perform TaTME.
Richard J. Heald, CBE, MChir, one of the pioneers of traditional TME, argued that careful excision along the holy plane—a plane outside and posterior to the rectum—would allow removal of the intact mesorectal envelope, with the tumor and any spreading cancer cells confined inside. Heald reported very low rates of local recurrence using this technique, which led TME to displace APR as standard of care for rectal tumors, with the exception of those that reside in the bottom third of the rectum. Few would contest that TME has revolutionized the field of rectal surgery, achieving similarly low levels of local recurrence as APR while better preserving function. However, critics have noted that the very low rates of recurrence reported by Heald have not been replicated, drawing into question his claim that better control could be achieved via TME.4
Some would speculate that the improved visibility and access provided by TaTME should lead to better margins and superior local control than with either APR or TME. However, a definitive answer to whether TaTME can improve long-term oncologic outcomes will have to await completion of long-term clinical trials.