Superior Mesenteric Vessel Anatomy Features Differ in Russian and Chinese Patients with Right Colon Cancer: Computed Tomography-Based Study
The surgical management of right colon cancer has been a topic of considerable interest, particularly regarding the role of extended lymph node dissection during right hemicolectomy. One of the key debates centers around the harvesting of lymph nodes located dorsally to the superior mesenteric vein (SMV) and superior mesenteric artery (SMA). The anatomy of the SMA and its branches, including the ileocolic artery (ICA), middle colic artery (MCA), and right colic artery (RCA), plays a critical role in determining the feasibility and safety of D3 lymph node dissection. The relative position of these branches to the SMV is particularly important, as it can significantly influence the technical difficulty of the procedure.
This study aimed to compare the frequency of SMA branches and their relative positions to the SMV in Russian and Chinese patients with right colon cancer. The findings reveal significant ethnic differences in the vascular anatomy of the right colon, which may impact the surgical approach and outcomes of extended lymph node dissection.
Background and Rationale
The SMA typically gives rise to three colic branches: the ICA, MCA, and RCA. The RCA, however, is not always present and has been reported in approximately 60% of cases. The position of these branches relative to the SMV is crucial for safe and effective D3 lymph node dissection. When the branches lie dorsally to the SMV, accessing their origins becomes more technically challenging, potentially complicating the procedure.
Computed tomography (CT) has emerged as a reliable tool for pre-operative assessment in colon cancer, allowing for detailed visualization of the vascular anatomy. This study utilized CT imaging to compare the vascular anatomy of the right colon in Russian and Chinese patients, focusing on the frequency of SMA branches and their relationship to the SMV.
Study Design and Methodology
A retrospective analysis was conducted on prospectively collected data from patients who underwent laparoscopic or robotic right hemicolectomy with D3 lymph node dissection at two major centers: one in Beijing, China, and the other in Moscow, Russia. The study included patients treated between 2016 and 2018. Patients with right colon cancer, defined as cancer located in the appendix, cecum, ascending colon, or hepatic flexure, were included. Those with a history of major abdominal resections or unclear/incomplete CT scans were excluded.
The study defined the MCA as the most cranial artery arising from the SMA and supplying the transverse colon, the ICA as the most caudal colic branch supplying the cecum, ileum, and appendix, and the RCA as a vessel originating directly from the SMA between the ICA and MCA. Cases where the RCA or MCA could not be identified as separate trunks were recorded as “RCA missing” or “MCA missing,” respectively.
Six types of arterial-venous interactions were defined based on the position of the ICA relative to the SMV: Type Ia (ICA ventral, RCA absent, MCA ventral), Type Ib (ICA ventral, RCA ventral, MCA ventral), Type Ic (ICA ventral, RCA dorsal, MCA ventral), Type IIa (ICA dorsal, RCA absent, MCA ventral), Type IIb (ICA dorsal, RCA dorsal, MCA ventral), and Type IIc (ICA dorsal, RCA ventral, MCA ventral).
Results
The study analyzed CT scan images from 260 patients, with 130 from each center. The Russian group had an almost equal distribution of men and women (66 and 64, respectively), while the Chinese group had a higher proportion of men (78 men and 52 women). Chinese patients were younger (mean age 58.8 years) compared to Russian patients (mean age 64.2 years), but the difference was not statistically significant. Body mass index (BMI) did not differ significantly between the groups.
All patients in the Russian group had both ICA and MCA, whereas two Chinese patients (1.5%) lacked the MCA. The RCA was significantly more frequent in the Chinese group (44.6%) compared to the Russian group (30.8%). The position of the ICA relative to the SMV also differed between the groups. In the Chinese group, the ICA was almost equally distributed between dorsal and ventral positions. In contrast, the Russian group showed a predominance of the ICA lying dorsally to the SMV (63 dorsal vs. 67 ventral in the Chinese group; 83 dorsal vs. 47 ventral in the Russian group). The most common distribution in the Russian group was Type IIa (43.8%), characterized by the ICA lying dorsally, RCA absent, and MCA lying ventrally.
Discussion
This study is one of the few to directly compare the vascular anatomy of the right colon between Russian and Chinese patients. The findings suggest significant ethnic differences in the anatomy of the SMA branches. Chinese patients were more likely to have the RCA as a separate trunk from the SMA, while Russian patients were more likely to have SMA branches lying beneath the SMV. These differences may influence the technical difficulty and outcomes of D3 lymph node dissection for right colon cancer.
The presence of the RCA as a separate trunk from the SMA was significantly higher in the Chinese group (44.6%) compared to the Russian group (30.8%). This finding aligns with previous studies suggesting that Eastern populations may have a higher prevalence of the RCA than Western populations. The position of the ICA relative to the SMV also varied significantly between the groups. In the Russian group, the ICA was more often located dorsally to the SMV, which is technically more challenging for surgeons during D3 lymph node dissection. In contrast, the ICA in the Chinese group was more often located ventrally to the SMV, making the procedure comparatively easier.
The technical challenges associated with D3 lymph node dissection are well-documented. Accessing the origins of the SMA branches is crucial for complete removal of tumor-related lymph nodes. When the ICA lies dorsally to the SMV, the surgeon must manipulate the SMV medially to reach the SMA trunk, increasing the complexity of the procedure. This anatomical variation is more common in the Russian group, suggesting that Western surgeons may face greater difficulties during D3 lymph node dissection compared to their Eastern counterparts.
Limitations
The study has several limitations, including its retrospective nature and the lack of intraoperative verification of the vascular anatomy. However, the use of CT imaging for vascular mapping has been validated in previous studies, making it a reliable tool for this analysis. The study also focused exclusively on patients with right colon cancer, which may limit the generalizability of the findings to other populations or conditions.
Conclusion
This study highlights significant ethnic differences in the vascular anatomy of the right colon between Russian and Chinese patients. Chinese patients were more likely to have the RCA as a separate trunk from the SMA, while Russian patients were more likely to have SMA branches lying beneath the SMV. These differences may impact the surgical approach and outcomes of D3 lymph node dissection for right colon cancer. Understanding these anatomical variations is crucial for surgeons to optimize their techniques and improve patient outcomes.
doi.org/10.1097/CM9.0000000000001566
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