July 15, 2016
Rectal cancer is one of the most challenging problems encountered by colorectal surgeons and a leading cause of cancer deaths in western countries. Mortality is mainly related to systemic spread of the disease before surgical resection, but locoregional recurrence after surgery is also associated with significant morbidity and mortality.
More recently, widespread adoption of neoadjuvant therapy and improved surgical techniques, especially total mesorectal excision (TME), have greatly reduced recurrent disease. TME, which is based on a better understanding of the local spread of rectal cancers, meticulously removes the tumor with its surrounding lymphatic tissues contained in a thin fascial layer. A complete TME is now considered a marker for good surgical technique and is the best predictor of cancer recurrence in the pelvis.
The advent of TME coincided with the increasing use of laparoscopic surgery to treat colon cancer, where minimally invasive techniques were associated with less postoperative pain and an earlier recovery than open colectomy, with similar oncologic outcomes. But minimally invasive surgery in rectal cancer is more complex, and the large randomized trials needed to establish laparoscopic proctectomy as an acceptable alternative to standard open procedures were never implemented.
Two such trials finally took place, with results published in The Lancet Oncology in 2013 and 2014. In both, the results for laparoscopic and open proctectomy were comparable for complete TME and uninvolved circumferential radial margin (CRM). Three-year local recurrence rates, disease-free survival and overall survival rates were also comparable.
Both trials had limitations, however, so another multicenter, noninferiority, randomized trial was conducted in the United States and Canada from 2008 to 2013. The results were published in JAMA in 2015.
The ACOSOG trial
That trial, the American College of Surgeons Oncology Group (ACOSOG) trial, evaluated 462 patients with stage II or III adenocarcinoma of the rectum at or below 12 centimeters above the anal verge. All patients had completed chemoradiotherapy or radiotherapy four to 12 weeks before surgery. A total of 240 patients were randomized to receive laparoscopic resection and the remaining 222 to receive standard open resection. All surgeons were credentialed before surgery.
The primary outcome was a composite of distal margin, CRM and total mesorectal excision quality. Complete TME was defined as a smooth surface of the mesorectal fascia and all fat contained in the enveloping fascia to a level 5 centimeters below the tumor; nearly complete TME meant that the mesorectal envelope was intact except for defects no more than 5 millimeters deep, with no loss of mesorectal fat.
Secondary outcomes included disease-free survival and rate of local recurrence as well as quality of life and benefits associated with laparoscopic resection such as blood loss, length of stay and use of pain medication.
The trial results showed the following:
- Complete TME in 77.1 percent of cases
- Nearly complete TME in 16.5 percent of cases
- Negative CRM in 87.9 and 92.3 percent of laparoscopic and open resections, respectively
- Negative distal margin result in more than 98 percent of patients, irrespective of type of surgery
- Nearly 87 percent overall surgical success (as measured by negative distal and CRM results and complete TME) in the open resection arm and 81.7 percent in the laparoscopic arm
- Conversion of laparoscopic to an open procedure in 11 percent of cases
The authors concluded that laparoscopic resection failed to meet the standard for noninferiority compared with open resection. Operative time was also considerably longer for laparoscopic resection, with a mean difference of more than 45 minutes, although length of stay, readmission within 30 days and severe complications (22.5 versus 22.1 percent, respectively) weren't significantly different.
Study author David W. Larson, M.D., a colon and rectal surgeon at Mayo Clinic's campus in Rochester, Minnesota, says although unexpected, the results cannot be attributed to the skill of the surgeons, who were all highly motivated, credentialed experts from major institutions.
He suggests that the challenges of working with rigid instruments in the curvature of the pelvis may be responsible and that different instrumentation or a robotic platform might improve outcomes. Even so, he and his colleagues question whether laparoscopic resection, even if noninferior, could be easily performed by general surgeons or colorectal surgeons who don't routinely use minimally invasive techniques in their practice.
Still, he points out that the long-term oncologic outcomes aren't yet available and that positive outcomes could potentially change the current recommendation against the use of laparoscopic resection for rectal cancer.
For more information
Van der Pas MH, et al. Laparoscopic versus open surgery for rectal cancer (COLOR II): Short-term outcomes of a randomised, phase 3 trial. The Lancet Oncology. 2013;14:210.
Jeong SY, et al. Open versus laparoscopic surgery for mid-rectal or low-rectal cancer after neoadjuvant chemoradiotherapy (COREAN trial): Survival outcomes of an open-label, non-inferiority, randomised controlled trial. The Lancet Oncology. 2014;15:767.
Fleshman J, et al. Effect of laparoscopic-assisted resection vs open resection of stage II or III rectal cancer on pathologic outcomes: The ACOSOG Z6051 randomized clinical trial. JAMA. 2015;314:1346.