Titanium Clip and Dental Floss Traction Assisted Endoscopic Submucosal Dissection Resection for Early Gastric Cancer

This study presents a successful technique using a titanium clip and dental floss traction-assisted endoscopic submucosal dissection for the treatment of early gastric cancer.

Endoscopic mucosal dissection (ESD) is used to diagnose and treat early gastrointestinal tumors. ESD allows for curative resection of superficial gastrointestinal lesions, with the advantage of treating multiple lesions in a single session and performing repeated procedures when necessary. However, ESD operations require a large field of view, and when bleeding occurs, the restricted space may make it difficult to locate and control the bleeding site in a timely manner. Larger wounds created during ESD procedures require even more space, and while tunneling technology has emerged, it is still considered less direct compared to having an additional hand to open the peeled mucosal window. Although transparent caps can help expose the surgical field, their effectiveness is limited when dealing with larger wounds. Various auxiliary techniques have been explored to address these challenges. In our endoscopic diagnosis and treatment center, we have been using ESD for many years, performing approximately 200 cases annually of gastric mucosal lesions and submucosal masses. The vertical and horizontal margins were negative, and the resection was complete, avoiding surgical treatment. Among these cases, 10 involved the use of dental floss-assisted traction during ESD. Dental floss assistance, as one of the auxiliary ESD methods, has the advantages of convenience and ease of use, which facilitates the imaging process. By securing the tail of a titanium clip with dental floss, the procedure becomes more efficient and adaptable. The traction wire can be pulled as needed during the operation, helping to expose and control the field of view. This significantly supplements the effect of the transparent cap, which may be less effective in larger wound areas. Dental floss traction acts as a third hand, expanding the operational space, facilitating endoscopic maneuvers, reducing surgical time, and minimizing the risk of side injuries during the treatment.

Endoscopic submucosal dissection (ESD) is a minimally invasive method for treating early gastrointestinal cancer and precancerous lesions¹. It involves the gradual dissection of gastrointestinal lesions, including early tumors, using high-frequency electric knives and specialized instruments under endoscopic guidance to achieve complete resection of the lesion². Due to the large field of view required during ESD, larger wounds demand more operational space³. If bleeding occurs in such cases, a small operating space may prevent the timely identification and control of the bleeding site³. While transparent caps are used to help expose the surgical field, their effectiveness in large wound areas remains limited⁴. It is generally considered more effective to use a third-hand approach to open the mucosal window for peeling⁵. As a result, numerous ideas and attempts have been made to incorporate auxiliary accessories to enhance the procedure.

Our endoscopic diagnosis and treatment center has been using this ESD technology for many years. For the removal of large gastric mucosal lesions, we use titanium clips and dental floss to assist in ESD, which offers convenience and ease of use. The core principle of dental floss-assisted ESD is to secure the mucosa at the window opening with a titanium clip, which is then connected to a traction wire -- dental floss -- outside the oral cavity⁵. This allows for on-demand pulling of the traction wire during the procedure to help expose and control the field of view, providing significant support to the transparent cap⁶. This method helps prevent issues that may arise from the unintentional continuous expansion caused by the limited field of the transparent cap⁷. As a powerful third hand, dental floss traction expands the operational space, facilitates endoscopic procedures, shortens surgical time, and reduces the risk of side injuries during treatment⁸. This dental floss-assisted traction method has been well-validated in our center. The overall goal of this method is to enhance the safety and efficiency of endoscopic submucosal dissection (ESD) for the removal of large gastric mucosal lesions by providing better control and visualization during the procedure.

This study was approved by the Shanghai Civil Aviation Hospital Committee (Ethics Approval No: 2023-06). Informed consent has been obtained from all patients. All ESD procedures were performed by a well-experienced gastroenterologist who had extensive training and practice in performing upper gastrointestinal ESDs. Specifically, the surgeon had more than 10 years of experience performing ESD and had completed over 150 procedures annually.

1. Preoperative preparation

1. Ensure the patient fasts for at least 8 h before surgery and administer intravenous fluids to prevent hypoglycemia and maintain electrolyte balance.
2. Before the surgery, determine the scope, nature, and invasion depth of the lesions by combining intensive endoscopic examination. Adjust the gastroscope settings to the Blue Light Imaging (BLI) mode for optimal imaging. Perform intensive endoscopic examination focusing on observing the microsurface structure (MS) and microvascular structure (MV).
3. Perform tracheal intubation for general anesthesia. Administer proton pump inhibitors 1 h before surgery to prevent bleeding.
   NOTE: Prior to undergoing intensive gastroscopy, it is recommended to take medications that help remove gastric mucus, such as streptomycin protease, and agents that eliminate foam in the stomach, such as simethicone. The Fuji 7000 endoscopy system utilized in our unit is equipped with advanced intelligent dyeing technology, including Blue Light Imaging (BLI) and optical magnification capabilities. The intensive gastroscopy diagnosis adheres to the Magnifying Endoscopy Simple Diagnostic Algorithm for Early Gastric Cancer (MESDA-G).

2. Gastroscopic exploration

1. After administering general tracheal intubation anesthesia, perform gastroscopy on the patient with gastric cavity gas insufflation achieved by using the inflation button.
2. Utilize the suction button to remove fluid and mucus from the stomach and throat.
3. After scrupulously exploring and rinsing the mucosa with water, confirm the location of the tumor under the white light of gastroscopy. Identify the specific location of the lesion based on the detailed gastroscopy examination results.
4. After the exploration, completely aspirate the CO₂ and fluid in the stomach and the fluid and mucus in the esophagus and throat.

3. Scope marking and sufficient exposure of lesions

1. Define the lesion boundary and mark it with an electric knife, maintaining a 5 mm margin from the lesion's edge.
2. Perform multi-point submucosal injection on the outer side of the marked point at the edge of the lesion.
3. Inject a mixture of physiological saline, sodium hyaluronate, methylene blue, and adrenaline beneath the lesion, with a volume of approximately 1 mL each time. The mixture consists of 100 mL of physiological saline, combined with 0.2 mL of methylene blue, 40 mg of sodium hyaluronate, and 1 mg of adrenaline hydrochloride.

4. Endoscopic submucosal dissection of the lesion

1. Use an electric knife to incise the mucosa around the lesion's edge, cutting into the submucosal layer.
2. Use titanium clips and dental floss to assist in traction during surgery as described below.
   1. Open the titanium clip, take a suitable length of dental floss, tie and fix the floss to one foot of the titanium clip, and knot the dental floss at the tail of the titanium clip.
   2. Close the titanium clip and insert it into the biopsy channel. Deploy the clip into the gastric cavity, attach it to the lesion's edge, and gently pull the dental floss to lift the mucosa.
   3. Gently pull the dental floss to pull up the mucosa and expose the boundary of the tumor.
3. Before performing dissection, assess the lifting status of the lesion, and maintain sufficient lifting of the lesion. Fully lift the lesion, carefully separate it along the submucosa, and achieve complete resection. Ensure to completely dissect the mucosal lesion and completely remove the lesion in one go. The settings used for completely lifting the lesion are Mode: Endocut (for cutting), 40 W, effect 3, cutting width 3, cutting interval time 3.
   NOTE: Adequate lifting of the lesion is beneficial for completely removing the lesion without easily damaging the intrinsic muscle layer, reducing the occurrence of complications such as perforation and bleeding.
4. Perform local electrocoagulation hemostasis with hot biopsy forceps during the operation.
5. Completely remove the lesion from the body. If the lesion size is large, extract the specimen using an endoscopic basket. After detaching the specimen, promptly extend and fix it as described in step 7 to prevent tissue ischemia or drying, which could interfere with pathological diagnosis.

5. Closure of the gastric wall defect

1. Perform hot biopsy forceps for local electrocoagulation hemostasis of wounds.
2. Gradually close the wound with metal titanium clips to ensure complete sealing. Use the following settings: Mode: Forced Coagulation (for hemostasis): 40 W, effect 2.

6. Surgical wound check

1. Inspect the wound surface carefully to confirm the absence of active bleeding. Completely aspirate any residual gas and fluid from the stomach cavity.
2. Place a gastric tube in the gastric cavity and withdraw the gastroscope.
3. Administer intravenous antibiotics to prevent infection. Administer a proton pump inhibitor (PPI) to promote wound healing and reduce the occurrence of postoperative bleeding.

7. Specimen management

1. Inspect the specimen visually to confirm its integrity and initial condition.
2. Flatten the specimen fully using tweezers and stainless-steel needles, then secure it onto a fixation plate.
3. Photograph the specimen and document its dimensions.
4. Immerse the specimen entirely in a 4% neutral formalin solution for fixation.

8. Postoperative care and monitoring

1. Monitor closely for any signs of bleeding, including changes in vital signs (heart rate, blood pressure), abdominal pain, the color of gastric tube drainage fluid, vomiting blood, and fecal occult blood.
2. Assess the patient's health status by monitoring abdominal pain and fever.
3. Ensure long-term endoscopic follow-up after surgery. Pathologically, for patients with high-grade intraepithelial neoplasia, perform gastroscopy follow-up 3-6 months after surgery, followed by another examination 12 months later. For patients with low-grade intraepithelial neoplasia, perform gastroscopy re-examination at 12 months post-surgery.

From 2021 to 2024, 10 patients with gastric mucosal lesions underwent ESD assisted by titanium clip and dental floss traction (Table 1). All diagnoses were confirmed by pathological examination, and none required conversion to open surgery. The average age was 69 years. Location of the tumor: four in the esophagus, two in the gastric body, two in the gastric antrum, two in the gastric angle, and one spanning the gastric antrum and angle. Out of the 10 lesions, eight were pathologically classified as high-grade neoplasia, or in situ cancer, and two were pathologically classified as low-grade neoplasia. The average area of esophageal lesions was close to the circumference. The average tumor size of the gastric was 3.5 cm.

The average operation duration was 82 min, and the average intraoperative blood loss was 8 mL. All patients resumed oral fluid consumption 48-72 h after surgery, and the average postoperative hospital stay was 4.5 days. All cases had negative tumor margins, and there were no perioperative complications. Out of 10, eight patients received regular follow-up, including gastroscopy. There were no gastric lesions (Figure 1) recurrences. The remaining two patients have not yet reached the endoscopic follow-up time.

All patients in this cohort achieved excellent oncological outcomes with minimal invasiveness and complete resection. There were no positive tumor margins or recurrences, and intraoperative blood loss was less than 10 mL. The average operation duration was under 2 h. Postoperatively, all patients experienced enhanced and smooth recovery, with an average hospital stay of 5 days. A photograph of an example specimen is shown in Figure 2.

Figure 1: Intraoperative gastroscopy. (A) The green arrow indicates the mucosal lesions under Blue Light Imaging (BLI). (B) The green arrow indicates the traction of the lesion using titanium clips and dental floss during surgery. Please click here to view a larger version of this figure.

Figure 2: Example photograph of the lesion removed. A titanium clip is present, with visible dental floss attached to it (red arrows). Please click here to view a larger version of this figure.

Table 1: Clinical parameters of 10 cases.

The prognosis and staging of gastric cancer are related to early diagnosis⁹. Early detection and treatment significantly reduce the mortality rate and improve outcomes for patients¹⁰. This underscores the importance of identifying and effectively managing precancerous lesions in the gastric mucosa¹⁰. Epithelial intraepithelial neoplasia, also known as dysplasia or atypical hyperplasia, belonging to precancerous lesions, is classified according to the degree of cellular and structural heterogeneity: low-grade intraepithelial neoplasia (LGIN) and high-grade intraepithelial neoplasia (HGIN)¹¹. Intraepithelial neoplasia of gastric mucosa, as a precancerous lesion of gastric mucosa, is closely related to gastric cancer and has the potential for carcinogenesis¹¹. Notably, some patients initially diagnosed with LGIN through biopsy are found to have upgraded pathology after undergoing endoscopic submucosal dissection (ESD)¹². With the advancement of endoscopic technology and the enhancement of people's health awareness, many gastric cancer patients are still in a state of being diagnosed¹⁰. In early-stage cancer, endoscopic mucosal dissection (ESD) is the main method for endoscopic treatment of early gastric cancer¹. ESD has a larger resection range, which can remove tissues with larger lesion areas in one go, send the lesion intact for examination, and has a good therapeutic effect, minimal trauma, and fast recovery².

For large-scale lesions or challenging anatomical areas where the submucosal layer is difficult to expose, endoscopic submucosal dissection (ESD) often requires auxiliary techniques, particularly traction methods¹³. To minimize the risk of perforation complications during the dissection of extensive lesions, submucosal tunneling endoscopic resection (STER) is employed for certain submucosal masses¹⁴. STER is primarily designed for tumors located in the intrinsic muscle layer of the esophagus and gastroesophageal junction¹⁵. However, this method can be time-consuming and technically demanding, requiring advanced surgical skills¹⁶. Additionally, STER may not be suitable for all patients and necessitates a comprehensive evaluation based on factors such as tumor size, location, and depth¹⁶. Both external and internal traction can significantly enhance the visibility of the submucosal layer, making it easier to perform precise resections¹⁷. Traction-assisted ESD can greatly reduce complications such as bleeding and perforation during surgery, thereby decreasing patient medical expenses and overall healthcare costs¹⁷. Additionally, by minimizing surgical complications, patient recovery times improve, and postoperative discomfort is significantly reduced¹⁷.

With the increasing demand, auxiliary methods for ESD treatment have also emerged¹⁷. These include dental floss assistance, heavy hammer clamp assistance, bending clamp assistance, and even more advanced approaches like dual clamp-assisted ESD and robot-assisted ESD^5,6,7,8. Robotic-assisted ESD holds promise for improving the precision and outcomes of endoscopic submucosal dissection, especially in complex cases¹⁸. However, the high cost, specialized training requirements, and limited accessibility in some settings may pose challenges¹⁸. As technology continues to advance, robotic systems are likely to become more integrated into ESD procedures, potentially expanding their availability and reducing barriers to use¹⁹. Among these methods, dental floss assistance stands out due to its simplicity, convenience, and ease of use⁵. This technique involves knotting and securing dental floss at the tail of a titanium clip, which eliminates the need for dual clamps during surgery⁶. Dental floss, made from durable plastic with excellent toughness and elasticity, is difficult to break and offers robust traction properties for internal use^5,6,7. The core principle of dental floss-assisted ESD is to fix the pre-cut lesion mucosa with a titanium clip, which is connected to a traction wire (dental floss) extending outside the body through the oral cavity^5,6,7. By enabling precise, on-demand pulling of the traction wire during the procedure, this technique provides superior visualization and control^5,6,7,8. It serves as an effective complement to the transparent cap, addressing its limitations in creating adequate operative space^5,6,7,8.

Several technical considerations are crucial for the successful implementation of dental floss-assisted ESD. Firstly, knot the dental floss at the end of the titanium clip, and be careful not to let the knot loosen. Second, the traction force applied to the dental floss can be flexibly adjusted according to the needs of the procedure or the size of the wound detachment area. By applying sufficient tension to the dental floss, the submucosal layer is exposed more clearly while minimizing the risk of damaging the underlying muscle layer and preventing perforation. Thirdly, the titanium clip can freely enter and exit the endoscopic channel, reducing the tedious steps caused by repeated entry and exit of the endoscope. In addition, by strategically applying traction, the surrounding tissues (e.g., muscularis propria or blood vessels) are less likely to be subjected to unwanted pressure or distortion during the dissection. This can lead to reduced complications such as perforation or bleeding. The force exerted by the traction (whether through floss, clips, or other devices) is transmitted through the tissue, generating a mechanical response that can stretch or reposition the tissue in a way that optimizes the dissection process. This effect may involve both elastic and viscoelastic properties of the tissue, which can change depending on the type of traction applied.

There are some limitations to this method. First, although dental floss is a good adjunct to ESD treatment, there is a possibility of tissue damage that needs to be taken into account when using it. For example, when dealing with lesions in the gastric angle, attention should be paid to the pressure and damage of dental floss on the cardia and pharynx during the operation. Second, consideration of the traction foothold. The traction landing point should be at the edge of the lesion and the starting point of the traction direction to ensure the traction effect. Moreover, the coordination of traction force and under-camera operation. Only through tacit cooperation can improve efficiency and reduce costs. In addition, dental floss traction may not be ideal for all types of lesions. Dental floss traction-assisted ESD is effective in the gastric body, antrum, and other areas; however, it may not be suitable for the upper part of the stomach (fundus and cardia) or the duodenum. Surgeons should select the appropriate traction technique or consider direct ESD based on the specific anatomical location and characteristics of the lesion to ensure both surgical safety and effectiveness. Moreover, we should pay attention to the risk of titanium clip detachment during dental floss traction ESD treatment. Floss detachment is a potential issue in dental floss traction-assisted ESD; however, it can be effectively managed through timely evaluation, refixation, or the use of alternative traction methods. Adequate preoperative preparation, standardized intraoperative procedures, and effective teamwork are essential in preventing floss loss. Surgeons should adapt their surgical strategy based on the specific situation to ensure both safety and effectiveness.

In the future, the use of new auxiliary traction methods will bring even more advantages to ESD surgery. The latest advancements in endoscopic traction techniques and potential future directions for ESD include innovations in robotics, artificial intelligence, and enhanced imaging technologies²⁰. Robotic-assisted systems are improving precision and control during procedures, while artificial intelligence is being integrated to assist in lesion detection, real-time navigation, and optimizing surgical outcomes²¹. Additionally, advanced imaging modalities, such as augmented reality and enhanced endoscopic techniques, are enabling better tissue visualization and more accurate dissection²². These innovations are expected to further enhance the effectiveness, safety, and efficiency of ESD procedures in the future^20,21,22. In summary, titanium clip dental floss-assisted traction is suitable for ESD resection surgery in the treatment of large-scale gastric mucosal lesions. It allows for complete resection of early gastric cancer under endoscopy while minimizing the drawbacks typically associated with surgical procedures.

The authors have nothing to disclose.

This work was supported by the Scientific research project of the Health and Wellness Committee, Changning District, Shanghai (No. 2023QN30), the Scientific research project of the Health and Wellness Committee, Changning District, Shanghai (No. 20233010), and the Foundation of Shanghai Civil Aviation Hospital Project (No. 2024mhyk001).