The surgery was successfully completed with the magnetic anchor device that we designed and manufactured. Throughout the procedure, the interaction force between the magnets provided the required mucosal exposure and mucosal tension for the surgery. In addition, by changing the position of the AM, the magnitude and direction of the pulling force on the TM could be flexibly changed to obtain the most suitable mucosal surface exposure and tension. This experiment showed that MAT-ESD is a potentially feasible procedure for the treatment of early-stage colorectal cancer.
ESD has become the standard of care for early-stage cancer. This endoscopic procedure can enable the early detection and diagnosis of cancer and improve the survival rate of patients. However, ESD also has many disadvantages, such as a difficult operation procedure, a long learning curve, a long operation time, and a higher risk of complications (e.g., bleeding, perforation, and stricture) [18, 19]. To overcome these shortcomings, a series of assistive technologies have emerged, such as the percutaneous traction-assisted method [22], S–O clip traction-assisted method [23], mucosal forceps channel-assisted method [24], clip-band traction-assisted method [25], sinker system traction-assisted method [26], ‘medical ring’ traction-assisted method [27], dual-scope endoscopy [28] (which is a novel flexible endoscopic surgical platform) [29], and a Master And Slave Transluminal Endoscopic Robot (MASTER) [30]. Although the above procedures can assist endoscopic operations, they cannot flexibly adjust and change the traction direction and traction force on the mucosa, and some endoscopic platform technologies are difficult to apply on a large scale in clinical practice.
MAT is a type of magnetic surgery, and is an ESD-assist technology with broad application prospects. The application of the mutual attraction between magnets has great potential in controlling the direction of traction and the magnitude of the traction force. The application of this technique not only reduces surgical trauma and interference between surgical instruments but also improves the exposure of the surgical field and the maneuverability of the surgical instruments [31]. The magnetic materials originally used for magnetic anchor devices were mainly electromagnets and permanent magnets [32], but because electromagnets are large, bulky objects, permanent magnets are now widely used for the special structure of the digestive tract [33].
MAT-ESD has been applied in the treatment of early-stage colorectal cancer [34]. Our magnetic device not only meets the magnetic requirements of surgery but also minimizes the volume of the TM and allows it to adapt to the special structure of the alimentary canal provided the ratio of the diameter to the height of the bottom of the TM cylinder is 1:2–1:1.5. The TM is covered with a permalloy shell, which can eliminate the interference of other instruments during surgery. In addition, a round hole with a diameter of 1 mm is present in the tail of the TM, which is convenient for connecting the TM to the soft-tissue clip.
Some limitations of this experiment must be acknowledged. First, the experiment was an ex vivo experiment, which cannot evaluate the tolerance of the operation in vivo and the risk of postoperative complications, such as bleeding and strictures. Second, the influence of the abdominal wall thickness, abdominal circumference, lesion location, and lesion size on the surgery could not be assessed. However, this study successfully completed the ex vivo experiments using an optimized MAT, thereby laying the foundation for subsequent in vivo animal experiments and human clinical trials.