[Transanal lateral lymph node dissection surgery for 5 cases of mid-low rectal cancer]

Objective: To evaluate the feasibility and safety of transanal lateral lymph node dissection for mid-low rectal cancer. Methods: A descriptive case series research method was used. Clinical and pathological data of 5 mid-low rectal cancer patients who underwent transanal lateral lymph node dissection at Department of Colorectal Surgery, the Sixth Affiliated Hospital of Sun Yat-sen University from November 2018 to May 2019 were retrospectively collected and analyzed. Of 5 cases, 4 were male and 1 was female with mean age of (43.2±13.2) years and mean body mass index of (21.2±2.6) kg/m(2); the mean diameter of tumor was (3.2±2.4) cm; the mean distance between tumor and anus was (6.3±2.5) cm; 3 received preoperative neoadjuvant chemotherapy. In preoperative TNM staging, 2 cases were T3N1M0, 1 was T3cN2aM0, 1 was T3cN2bM0, and 1 was T2N1M0. All the patients had no intestinal obstruction before operation. Surgical methods: (1) total mesorectal excision: using general transanal and transabdominal methods to mobilize and resect total mesorectum, and dissect No.252, No.253 lymph nodes; (2) transanal lateral lymph node dissection: dissect the adipose lymphoid tissue on the surface of the iliococcygeal muscle, the coccygeal muscle, and the obturator muscle (the No.283 lymph nodes) upward, and dissect No.263d and No.263p lymph nodes with fat tissue sequentially till the bifurcation of the internal and external iliac artery; (3) take out the specimen from anus, and make anastomosis between proximal colon and anal canal. Intraoperative and postoperative variables was observed. Results: All the 5 patients completed surgery successfully, and no patient needed to convert to open approach. The mean operative time was (295.6±97.7) minutes, and the median intraoperative blood loss was 70 (50-500) ml. The mean length of specimen was (12.9±3.0) cm, and the mean number of harvested lymph node was 30.4±9.9. The positive lateral lymph nodes were founder in 4 patients. The median distance between tumor and distal resection margin was 1.5 (1.2-8.0) cm. The resection margin in all the patients was negative. The mean time to postoperative flatus was (4.2±1.6) days, the mean postoperative spontaneous urination was (3.0±1.9) days, time to drainage tube removal was (5.6±1.9) days, and the mean postoperative hospital stay was (9.4±2.1) days. The postoperative TNM staging by pathology was 1 case with T1N0M0, 1 with T2N1M0, 1 with T3N2bM0, and 2 with T3N2M0. Five patients were moderately differentiated adenocarcinoma. Only 1 patient developed postoperative abdominal bleeding, who was healed after conservative treatment. The other 4 patients did not develop any perioperative complications, such as incision infection, presacral abscess, pelvic abscess, anastomotic leakage, or anastomotic stricture. Four patients underwent postoperative chemotherapy. All the patients were followed up for 2 to 28 weeks after surgery and they all felt well. The patients with stoma had fluent bowel. Conclusions: Transanal lateral lymph node dissection is feasible and safe in the treatment of mid-low rectal cancer, which can achieve the purpose of extended radical resection of mid-low movement rectal cancer. Moreover, this procedure is a new method to treat rectal cancer patients with lateral lymph node metastasis.