Comments on Superior Mesenteric Artery First Approach for Right Colectomy

We read the article by Luo et al.[Luo W, Cai Z, Li F, Lu T, Xu Z, Jia Y, et al. Laparoscopic complete mesocolic excision with central vascular ligation (CME + CVL) for right-sided colon cancer: a new “superior mesenteric artery first” approach. Ann Surg Oncol. 2022;29(8):5066–73. https://doi.org/10.1245/s10434-022-11773-0 .] with great interest. There are some points we would like to address. In the superior mesenteric artery first approach, the dissection is started in the cranial part of the superior mesenteric artery (SMA), outside the vascular sheath, in order to preserve autonomic nerve function. The colic arteries are ligated at their origin. The surgical trunk of superior mesenteric vein (SMV) and the jejunal veins, if they cross anteriorly, are skeletonized. In our hands, the dissection is less complicated, and the colic branches (middle colic artery, right colic artery, and ileocolic artery) are found easier if the arterial sheath is incised. The vascular sheath is the perfect layer to operate in, and by doing so, one gets to the D3 volume from outside, minimizing the spillage of lymphatic fluid, which can contain cancer cells. In our procedure, the extent of injury to the superior mesenteric nerve plexus is 48% of the area.2 A study3 has shown that the effect of such injury to the nerve plexus on the patient’s bowel function is comparable to that of patients who have undergone traditional D2 mesenterectomy. In our practice, we use preoperative 3D-reconstructed abdominal computed tomography (CT).4 The reconstruction functions like a roadmap for surgery covering the whole SMA/SMV surgical trunk where syntopy between the arteries and veins is depicted. Vascular abnormalities,5 which appear in approximately 10% of patients, can be recognized and planned for in advance of the operation with the reconstructions. The body mass index (BMI) of the patients in the article is low compared with the BMI of the patients with colonic cancer in Western Europe. In our opinion, it would be difficult to find and dissect along the SMA, starting cranially, in patients with high BMI and excess fat in the mesocolon. With the vascular map, the dissection can start near the ileocolic vessels, which we think is a safer approach. Any vascular accident at this level has little consequences compared with injury to the proximal SMA or SMV. Any jejunal veins crossing AMS anteriorly will also be recognized ahead of the operation. As stated in the article, there is no consensus regarding the medial border for right colectomy when treating cancer. Lymphatic tissue draining the right colon has been found anterior and posterior to the mesenteric blood vessels.6,7 Lymph vessel trajectories have been mapped out in an anatomical study,6 and lymph vessels draining the right colon were found in front of SMA in 14 of 16 cadavers. With these results in mind, our group have proposed the left edge of SMA as the medial border for right colectomy when treating cancer. With the procedure ‘‘right colectomy with extended D3 mesenterectomy: anterior and posterior to the mesenteric vessels,’’8,9 which can be performed with an open, laparoscopic, or robot-assisted approach, the removal of lymphatic tissue in front of and behind SMA

Defining minimal clearances for adequate lymphatic resection relevant to right colectomy for cancer: a post-mortem study

Background There has been a lengthy discussion on the extent of lymphatic resection for right-sided colon cancer and the central borders of the mesentery that are not yet defined. The objectives of this study are to define minimal clearances for adequate lymphatic resection in regard to colic artery origins and the superior mesenteric artery (SMA) and vein (SMV) relevant to right colectomy. Methods Central mesenteric lymph vessels, nodes, and blood vessels were dissected in 16 cadavers. Cranial–caudal clearances were defined as distances between an individual colic artery origin (ileocolic, right colic, and median colic artery) and the outermost lymphatic vessel within its lymphovascular bundle, cranial and caudal along the SMA. Long lymphatic vessels crossing the SMV between arterial bundles were counted and they constituted the medial clearances. An arbitrary watershed between small bowel and colonic lymph was localized. Immunohistochemistry was performed to histologically verify lymphatic vessels. Results Cranial–caudal clearances were ileocolic 3.6 ± 1.9 and 5.7 ± 1.9; right colic 2.8 ± 1.6 and 3.3 ± 1.0; middle colic artery bundle 6.3 ± 2.7 and 5.9 ± 2.4 mm, respectively. Long lymphatic vessels crossing the SMV between arterial buntles and approaching the SMA were found in all cadavers (antero/posteriorly in 12, only anteriorly in 4), median 3.5 (1–7) long lymphatic vessels anteriorly, and 1.5 (0–5) posteriorly per cadaver. Conclusions Right colonic lymphovascular bundles are volumes of mesenteric tissue that surround the superior mesenteric vessels anteriorly and posteriorly. Long lymphatic vessels traverse the superior mesenteric vein anteriorly/posteriorly approaching the superior mesenteric artery between arterial bundles and placing the medial clearance on the left side of the artery. These do not correlate to arterial crossing patterns. Cranial–caudal clearances determine the tissue to be removed superior/ inferior to arterial origins together with long lymphatic vessels transversing independently between the lymphovascular bundles placing the weight of lymphatic resection on the mesenteric tissue and not on the level of vessel division (High tie)

Bowel motility after injury to the superior mesenteric plexus during D3 extended mesenterectomy

Background: Improvement of lymphadenectomy in right colectomy requires removal of all tissue surrounding the superior mesenteric vessels beneath the pancreatic notch. Shortand long-term bowel motility disorders after D3 extended mesenterectomy with consecutive superior mesenteric plexus transection are studied. Methods: Patients without pre-existing motility disorders undergoing D3 extended mesenterectomy were examined 3 times using the wireless motility capsule: before, at 3 wk, and 6 mo after surgery. Segmental transit times and contractility were analyzed using mixed effect modeling. Correlation between contractility and transit time was assessed by the Pearson correlation coefficient. Results: Fifteen patients (4 men), with median age 62 y, were included. Mean values for the three consecutive examinations are as follows. Gastric transit time increased from 237 to 402 and 403 min, respectively. Small bowel transit time decreased from 246 to 158 (P < 0.01) and 199 (P ¼ 0.03) min, respectively. Colonic transit time decreased from 1742 to 1450 and 1110 (P ¼ 0.02) min, respectively. Gastric contractions per minute (CPM) varied from 1.73 to 1.05 (P ¼ 0.01) and 2.47 (P < 0.01), respectively. Small bowel CPM decreased from 3.43 to 2.68 and 3.34, respectively. Colonic CPM ranged from 1.59 to 1.45 and 1.91 (P ¼ 0.08), respectively. Correlation between small bowel (SB) transit time and CPM was _0.45 (P ¼ 0.09) preoperatively, and _0.03 (P ¼ 0.91) 6 mo postoperatively. Conclusions: Extrinsic SB denervation leads to significantly accelerated SB transit, reduced contractility, and disturbed correlation between transit time and contractility early after denervation. Both number of contractions and transit time in the denervated SB show a clear tendency toward normalization at 6 mo

The anatomical and surgical consequences of right colectomy for cancer

Current practice when performing right colectomy for cancer is to divide the feeding vessels for the right colon on the right side of the superior mesenteric vein

Right colectomy with extended D3 mesenterectomy: anterior and posterior to the mesenteric vessels

BACKGROUND: In right colectomy for cancer, complete mesocolic excision and D3 lymphadenectomy each leave behind lymphatic tissue anterior and posterior to the superior mesenteric vein (SMV) and artery (SMA). In this article, we present D3 extended mesenterectomy: a surgical technique that excises the lymphatic tissue en bloc with the right colectomy specimen. MATERIAL AND METHODS: A 3D map of the mesentery of the right colon was reconstructed from staging CT-angiogram scans. The surgical technique of right colectomy with D3 extended mesenterectomy consisted of eight steps: 1) reveal the SMV and SMA; 2) isolate the ileocolic artery; 3) isolate the middle colic artery; 4) resolve the anterior mesenteric flap; 5) specimen de-vascularization; 6) colectomy; 7) resolve the posterior mesenteric flap; and 8) anastomosis. RESULTS: One-hundred-seventy-six patients (77 men) 66 years of age were operated upon from February 2011 to January 2017. There were 169 adenocarcinomas: 16.0% Stage I, 49.1% Stage II, 33.7% Stage III, 1.2% Stage IV. Tumor locations were 50.6% cecum, 41.5% ascending colon, 4.5% hepatic flexure, and 2.3% transverse colon. Mean operating time was 200 minutes, blood loss 273 ml, and length of stay 7.9 days. There were 9 anastomotic leakages and 15 reoperations. One patient underwent small bowel resection due to SMA tear. There was no postoperative mortality. The mean number of lymph nodes per specimen (40.9) was comprised of 27.1 in the D2 volume and 13.8 in the D3 volume. The mean number of metastatic lymph nodes was 1.2 in the D2 volume and 0.13 in D3. There were 7 patients with lymph node metastasis in D3, 2 of whom had node metastasis solely within D3. CONCLUSION: This study shows that 1.2% of patients would have been incorrectly diagnosed as Stage II if extended D3 mesenterectomy had not been performed. Similarly, lymph node metastases would have been left behind in 4.1% of patients if extended D3 mesenterectomy had not been performed

Are Metastatic Central Lymph Nodes (D3 volume) in right-sided Colon Cancer a Sign of Systemic Disease? A sub-group Analysis of an Ongoing Multicenter Trial

Objective: Assess outcomes of patients with right-sided colon cancer with metastases in the D3 volume after personalized surgery. Background: Patients with central lymph node metastasis (D3-PNG) are considered to have a systemic disease with a poor prognosis. A 3-dimensional definition of the dissection volume allows the removal of all central nodes. Materials and methods: D3-PNG includes consecutive patients from an ongoing clinical trial. Patients were stratified into residual disease negative (D3-RDN) and residual disease positive (D3-RDP) groups. D3-RDN was further stratified into 4 periods to identify a learning curve. A personalized D3 volume (defined through arterial origins and venous confluences) was removed " en bloc" through medial-to-lateral dissection, and the D3 volume of the specimen was analyzed separately. Results: D3-PNG contained 42 (26 females, 63.1 SD 9.9 y) patients, D3-RDN:29 (17 females, 63.4 SD 10.1 y), and D3-RDP:13 (9 females, 62.2 SD 9.7 y). The mean overall survival (OS) days were D3-PNG:1230, D3-RDN:1610, and D3-RDP:460. The mean disease-free survival (DFS) was D3-PNG:1023, D3-RDN:1461, and D3-RDP:74 days. The probability of OS/DFS were D3-PNG:52.1%/50.2%, D3-RDN:72.9%/73.1%, D3-RDP: 7.7%/0%. There is a significant change in OS/DFS in the D3-RDN from 2011-2013 to 2020-2022 (both P =0.046) and from 2014-2016 to 2020-2022 ( P =0.028 and P =0.005, respectively). Conclusion: Our results indicate that surgery can achieve survival in most patients with central lymph node metastases by removing a personalized and anatomically defined D3 volume. The extent of mesenterectomy and the quality of surgery are paramount since a learning curve has demonstrated significantly improved survival over time despite the low number of patients. These results imply a place for the centralization of this patient group where feasible.</p