Oncological outcomes of robotic-assisted laparoscopic versus open lateral lymph node dissection for locally advanced low rectal cancer

The aim of the study was to confirm the noninferiority of mesorectal excision (ME) alone to ME with lateral lymph node dissection (LLND) in terms of efficacy.

This study was designed to clarify indication and benefit of pelvic sidewall dissection for rectal cancer. The retrospective, multicenter study collected the data of rectal cancer patients who underwent surgery between 1991 and 1998 and were prospectively followed. Of 1,977 patients with rectal cancers, 930 underwent pelvic sidewall dissection without adjuvant radiotherapy. Positive lateral lymph nodes were found in 129. Multivariate analysis disclosed a significantly increased incidence of positive lateral lymph nodes in female gender, lower rectal cancers, non-well-differentiated adenocarcinoma, tumor size of > or =4 cm and T3-T4. The five-year survival rate for 1,977 patients was 79.7 percent. The survival of patients with positive lateral lymph nodes was significantly worse than that of Stage III patients with negative lateral lymph nodes (45.8 vs. 71.2 percent, P<0.0001). Multivariate analysis showed significantly worse prognosis in male gender, pelvic sidewall dissection, lower rectal cancers, T3-T4, perirectal lymph node metastasis, and positive lateral lymph nodes. During the median follow-up time of 57 months, recurrence developed in 19.7 percent: 17 percent in negative and 58.1 percent in positive lateral lymph nodes (P<0.0001). Local recurrence was found in 8 percent: 6.8 percent in negative and 25.6 percent in positive lateral lymph nodes (P<0.0001). Multivariate analysis disclosed that lower rectal cancers, non-well-differentiated adenocarcinoma, T3-T4, perirectal lymph node metastasis, and positive lateral lymph nodes were significantly associated with an increased local recurrence. Positive lateral lymph node was the strongest predictor in both survival and local recurrence. Pelvic sidewall dissection may be indicated for patients with T3-T4 lower rectal cancers because of the greater probability of positive lateral lymph nodes.

Mesorectal excision is the international standard surgical procedure for lower rectal cancer. However, lateral pelvic lymph node metastasis occasionally occurs in patients with clinical stage II or stage III rectal cancer, and therefore mesorectal excision with lateral lymph node dissection is the standard procedure in Japan. We did a randomised controlled trial to confirm that the results of mesorectal excision alone are not inferior to those of mesorectal excision with lateral lymph node dissection. This study was undertaken at 33 major hospitals in Japan. Eligibility criteria included histologically proven rectal cancer of clinical stage II or stage III, with the main lesion located in the rectum with the lower margin below the peritoneal reflection, and no lateral pelvic lymph node enlargement. After surgeons had confirmed macroscopic R0 resection by mesorectal excision, patients were intraoperatively randomised to mesorectal excision alone or with lateral lymph node dissection. The groups were balanced by a minimisation method according to clinical N staging (N0 or N1, 2), sex, and institution. Allocated procedure was not masked to investigators or patients. This study is now in the follow-up stage. The primary endpoint is relapse-free survival and will be reported after the primary analysis planned for 2015. Here, we compare operation time, blood loss, postoperative morbidity (grade 3 or 4), and hospital mortality between the two groups. Analysis was by intention-to-treat. This trial is registered with ClinicalTrials.gov, number NCT00190541. 351 patients were randomly assigned to mesoretcal excision with lateral lymph node dissection and 350 to mesorectal excision alone, between June 11, 2003, and Aug 6, 2010. One patient in the mesorectal excision alone group underwent lateral lymph node dissection, but was analysed in their assigned group. Operation time was significantly longer in the mesorectal excision with lateral lymph node dissection group (median 360 min, IQR 296-429) than in the mesorectal excision alone group (254 min, 210-307, p<0·0001). Blood loss was significantly higher in the mesorectal excision with lateral lymph node dissection group (576 mL, IQR 352-900) than in the mesorectal excision alone group (337 mL, 170-566; p<0·0001). 26 (7%) patients in the mesorectal excision with lateral lymph node dissection group had lateral pelvic lymph node metastasis. Grade 3-4 postoperative complications occurred in 76 (22%) patients in the mesorectal excision with lateral lymph node dissection group and 56 (16%) patients in the mesorectal excision alone group. The most common grade 3 or 4 postoperative complication was anastomotic leakage (18 [6%] patients in the mesorectal excision with lateral lymph node dissection group vs 13 [5%] in the mesorectal excision alone group; p=0·46). One patient in the mesorectal excision with lateral lymph node dissection group died of anastomotic leakage followed by sepsis. Mesorectal excision with lateral lymph node dissection required a significantly longer operation time and resulted in significantly greater blood loss than mesorectal excision alone. The primary analysis will help to show whether or not mesorectal excision alone is non-inferior to mesorectal excision with lateral lymph node dissection. National Cancer Center, Ministry of Health, Labour and Welfare of Japan. Copyright © 2012 Elsevier Ltd. All rights reserved.