A Randomized Controlled Tiral Of Apical Lymph Node Resection With Preservation Of Left Colic Artery In Rectal Cancer Surgery And The Study Of The Micrometastasis Of Apical Lymph Node

Objective:In the present study, we aimed to make a randomized clinical trial study to evaluate theinfluence of high and low ligation of the inferior mesenteric artery with apical lymph nodedissection on the anastomotic blood supply, lymph node retrieval rate, operative time, andanastomotic leakage rate in rectal cancer surgery. Besides, we examined the micrometastasisof the apical lymph node of the rectal cancer and looked for the potential correlated clinicaland pathological factors that may influence the apical lymph node micrometastasis. Wediscussed the necessity of preserving of the left colic artery with excision of the apical lymphin rectal cancer surgery.Methods:This study consists of two parts. In the randomized clinical trial study, Patients whomatch the inclusion criteria were randomly distributed into group A and group B andunderwent laparoscopic radical resection of rectal cancer. Patients in group A underwent highligation of the inferior mesenteric artery, and patients in group B underwent apical lymphnode resection around the root of the inferior mesenteric artery with preservation of the leftcolic artery. The marginal artery stump pressure was measured after colon and arteryreconstruction. Systemic pressure, distal colon length, operative time, and lymph noderetrieval rate were measured and recorded. The results were analyzed and related to patientcharacteristics and postoperative complications. In the study of the apical lymph nodemicrometastasis, we examined CK19expression of the apical lymph node via RT-PCR andimmunohistochemistry. We found the apical lymph node in the fresh specimens with the helpof pathologists. Each apical lymph node was divided into two parts. One part of the lymphnode was examined via RT-PCR, and the other part was embedded by wax in the PathologyDepartment and examined via immunohistochemistry. Besides, we also examined KRAS,NRAS and BRAF gene mutation of the corresponding rectal tumor, and analyzed the correlation of the apical lymph node micrometastasis and the gene mutation, and other clinicaland pathological factors.Results:In the randomized clinical trial study, a total of57patients were included in the study,29patients in group A and28patients in group B. In group A, the average marginal arterystump pressure was42.31±1.85mm Hg, the average overall lymph node retrieval numberwas16.21±1.08,the average apical lymph node retrieval number was2.96±0.39, the averageoperative time was166.00±9.15min. In group B, the average marginal artery stump pressurewas48.50±2.48mm Hg, the average overall lymph node retrieval number was17.71±1.36,the average apical lymph node retrieval number was2.96±0.47, the averageoperative time was180.00±10.80min. We found that the anastomotic blood supplynegatively and linearly correlated with age and distal colon length and showed a positivelinear correlation with systemic pressure. When the distal colonic length, systemic pressureand age was standardized to20.65cm,82.05mm Hg and60.72years respectively, themarginal artery stump pressure was41.30±1.92mm Hg and49.55±1.96mm Hg in group Aand group B (p=0.004). The result indicated that patients who received low ligation withapical lymph node dissection had a better anastomotic blood supply than those who receivedhigh ligation.3patients in group A and1patient in group B got anastomotic leakage. Nodifferences were found in lymph node retrieval rate, operative time, and anastomotic leakagerate. Anastomotic leakage was associated with a worse anastomotic blood supply. In thestudy of the apical lymph node micrometastasis, we harvested235apical lymph nodes from51patients in total.18among them were positive according to the routine postoperativepathology reports. The other217negative apical lymph nodes were examined via RT-PCRand immunohistochemistry. And we found13micrometastasis lymph nodes in12patients,with a micrometastasis rate of23.53%. The RT-PCR method found13lymph nodes withmicrometastasis and the immunohistochemical method found12lymph nodes withmicrometastasis.1patient’s lymph node micrometastasis was found by RT-PCR methodinstead of immunohistochemical method. For the TNM stage I, II, III, IV tumor, themicrometastasis rate was0%(0/7),10.53%(2/19),35.00%(7/20),60.00%(3/5)respectively.20among these51patients had a KRAS gene mutation in exon2, and3amongthese51patients had a NRAS gene mutation in exon3. No other mutation was found amongthe exon15of BRAF gene and other exon of KRAS gene and NRAS gene. Themicrometastasis of the apical lymph node was correlated with the KRAS gene mutation, TNM stage and vascular invasion of tumor. The KRAS gene mutation and TNM stage werethe independent risk factors for apical lymph node micrometastasis.Conclusions:The preservation of the left colic artery in rectal cancer surgery can ensure better bloodsupply for distal colon and anastomosis. The apical lymph node resection in rectal cancersurgery can resect the occult micrometastasis tumor in apical lymph node, especially for thepatients with tumor in TNM stage II and stage III or the patients with KRAS gene mutation,apical lymph node resection is very important. Low ligation with apical lymph nodedissection in rectal cancer treatment provides better anastomotic blood supply and won’taffect lymph node retrieval rate or operative time. The laparoscopic apical lymph nodedissection with preservation of the left colic artery in rectal cancer surgery is worthpromoting.