Lymph node metastasis is an important factor affecting postoperative local recurrence and 5-year survival rate of colorectal cancer, as well as an important basis for determining the operation mode of colorectal cancer [5, 6]. Complete lymph node dissection is an effective method to improve the cure rate of colorectal cancer. For patients with colorectal cancer, 253 lymph nodes should be removed completely to achieve D3 dissection [7, 8]. Previously, we severed the inferior mesenteric artery at the root to clean the 253 lymph nodes. Recently, to provide better blood supply at the anastomosis, we retain the left colic artery and then severed the inferior mesenteric artery, which improved the difficulty of dissecting 253 lymph nodes [9, 10]. Sometimes lymph nodes were left owing to the difficulty of the operation, especially for fat patients.
In actual clinical work, some surgeons prefer to dissect lymph nodes by intrathecal dissection. They think that the 253 lymph nodes could be cleaned completely by this method, specially lymph nodes behind the arteries. Besides, the surgical picture is very beautiful and has a high appreciation value. However, there was no published papers reporting this conclusion. Of course, there were disadvantages of this method, for example, stripping away the sheath of blood vessels may damage the vascular wall easily by the thermal damage of ultrasonic scalpel. In our study, there was one patient with rectal cancer underwent laparoscopic radical resection and the 253 lymph nodes were removed by intrathecal dissection. This patient present with anastomotic leakage and intra-abdominal bleeding after operation. Then he underwent a second operation, during which a defect was found in the inferior mesenteric artery. This patient died owing to hemorrhagic shock. The reason may be that there was vascular wall injury by ultrasonic scalpel and intestinal fluid eroded vascular wall following anastomotic leakage, resulting in vascular wall damage and bleeding.
Some other surgeons prefer to dissect lymph nodes by extracapuslar dissection, also named choroidal cleaning. This method is relatively safe as it retains the vascular sheath. These surgeons argue that this method could also clean the 253 lymph nodes completely. Up to now, there was no study to compare the results of these two methods.
As we known, our study is the first one to compare the curative effect and safety of these two methods. Our study showed that there were no statistic differences in the mean number of lymph nodes and positive lymph nodes harvested from the patients between the two groups. Besides, there was also no statistic differences in the nodal staging between the two groups. Therefore, we could conclude that dissecting lymph nodes by extracapuslar dissection had a similar curative effect compared to intrathecal dissection. However, the amount of bleeding in intrathecal group was significantly higher than that in extracapuslar group and the operation time in intrathecal group was also significantly longer. As a result, it was more traumatic to dissect lymph nodes by extracapuslar dissection than intrathecal dissection.