The number of colorectal cancer patients in the world ranks 3 of all types of tumor, and morbidity is on the rise in recent years[3, 9]. However, there are not enough hospitals and doctors that are capable to complete colorectal ESD operation, and patients in remote areas couldn’t get early treatment. The novel traction ring method was successfully applied in cases of our pilot trial. This simple technique does not require withdrawal and reinsertion of the colonoscope and takes only a few minutes to attain good visualization of the submucosal layer during procedure. We found that this method is feasible for colorectal ESD. We hope that ESD will be easier to learn by the traction ring, to reduce the difficulty for new scholars to master this practical technic, and can quickly promote ESD to large-scale application.
For colorectal, due to the special anatomical characteristic, such as the thin wall of colon, the existence of folds and curvature, etc., the technical difficulty of ESD is greatly increased. Difficult ESD is related to the prolongation of operation time, the decrease of en bloc resection rate and the occurrence of perforation. According to clinical research, some traction techniques are safe and effective in ESD treatment, which can reduce the difficulty of operation [8, 10]. At present, the traction methods in clinical research can be roughly divided into internal traction pattern, external traction pattern and special traction pattern. External traction pattern such as the clip with line method, grasping forceps [6, 11]. Grasping forceps could only be used in rectal lesion, and contact between the endoscope and the forceps causes them to interfere with each other . Clip with line method which is easily to obtain countertraction effect at rectum, but as in deep colon it may be strenuous because of difficulty in reinserting the endoscope and adjusting direction of traction. Moreover, controlling traction force precisely in the proximal colon is difficult because the air volume and peristalsis in the colon could strengthen the traction force, excessive traction may lead to the traction system slipped from the lesion or even laceration may occur. Clip with line method that can access to the deep colon have been reported, which does not require withdrawal and reinsertion of the endoscope . However, it is difficult to modulate the counteraction which is adjusted solely by pulling. Special equipment traction is obtained by additional equipment such as magnetic anchor, double scope method [7, 13]. These methods requires special equipment, which cost high and occupy large space. Double scope method is technically difficult to operate, and the technique is limited to the rectum and distal sigmoid colon because of difficulty in inserting the second endoscope into the oral side of the descending colon . Internal traction method was firstly introduced by Saito et al , which use sinker to supple the lack of counter traction provided by gravity. Internal traction method which stable and continuous traction exerted by the internal system avoid the interference by the operation, but placement of sinker needs exit of endoscope and patient needs to change position for cooperation. If traction device can pass through the working channel of endoscopy, there is no need to withdraw and reinsert the endoscope for traction system settlement. Simplified the operation will reduce air-filling volume, avoid deformation of intestinal tract and movement of lesion position. Endoscopists have developed such internal traction methods as silk thread, elastic band and S-O clip [8, 10, 15]. These methods could offer variety of traction direction meet the clinical need.
Therefore, we designed a new traction device "traction ring" which can be used in colorectal ESD. The materials are easy to obtain and manufacture of the ring is simple. The traction can be completed by matching with the clips which is commonly available. The Annular duct at both ends of the traction ring can assist doctors to locate and fix by clips, as to reduce the difficulty of setting the traction device. Besides, the design of the traction ring can avoid the situation that the tension on both ends of the elastic ring is unequal due to the asymmetry of the fixed position in the ESD operation. Internal traction can be achieved through traction ring, and will not be interfered by the physiological structure of the colon and movement of endoscope, such independence prevented paradoxical or unintended movements. In the colon that above sigmoid, especially the lesions at transverse and descending colon and cecum, satisfactory traction can also be obtained. By employed the same way to obtain countertraction in lower gastrointestinal lesions, will decrease the time cost of learning traction method.
Our retrospective study suggests that the traction ring is relatively successful in exposing the tumor margins for resection. Besides, the mean en bloc rate and R0 resection rate in our study respectively was 95% and 90%, which was the more than that the rate in the other reports [16–18], and this might be a potential advantage of this method. Preparation and retrieve of the traction system are quick and easy, settlement of the system never took more than 4 minutes, accounting for only 2.7% of the whole procedure time. All traction rings were successfully retrieved, and procedures were safely proceeded, none of the lesions was there damage caused by traction. The rate of adverse event which was the same or less than the rate of previous study [16–18]. Research shows that giant tumor, lateral developmental tumor, right hemicolon, severe fibrosis, deep invasion of T1 phase tumor are risk factors of perforation [19–20]. In our study, a patient with a 50 mm laterally spreading tumor located at splenic flexure suffered from perforation. Since it has been successfully closed during operation, no extra treatment was required.
This study has the following limitations: Firstly, the small sample size included in this retrospective study. Moreover, the patients included in this trial were according to operators’ preference. Further studies are required to verified the applicability of traction ring.