Gastrointestinal Tumors vs. Gastrointestinal Endoscopy – The Magic World Inspired by the sword swallowing performance of a magician, a German scholar developed the world’s first gastroscope in 1868, enabling doctors to directly observe the inside of the stomach. It was made of a straight metal tube and utilized the reflected light from a fuel lamp. Since then, after more than 100 years of continuous improvement and refinement, through the semi-flexible endoscopy, fiber-optic endoscopy, to the current electronic endoscopy, so that the mirror body has become more and more thin and soft, and can even be inserted through the nasal cavity and inspection operations, greatly reducing the degree of discomfort of the examination of the examination. At the same time, with the continuous development of magnification and other technologies such as pigmented endoscopy, the ability of endoscopy to identify lesions in the digestive tract has been continuously enhanced. The corresponding development of advanced electronic colonoscopy technology has made colorectal examinations increasingly acceptable. For those who are less tolerant, painless gastroscopy and painless colonoscopy techniques have been developed in recent years, including conscious sedation and intravenous anesthesia techniques, which have been widely used in clinical practice to greatly improve the comfort of the examinee. For the suspected lesions in the digestive tract, biopsy can be performed through endoscopy to further determine the nature of the lesions for histopathological examination. At present, gastroscopy and enteroscopy have become routine diagnostic means in medical units with digestive endoscopy technology. The recently developed small enteroscopy technology makes endoscopic examination of the curved and slender small intestine possible, while capsule endoscopy (also called wireless endoscopy) breaks through the traditional concept of endoscopy to be selectively applied to the diagnosis of suspected small intestinal lesions. The perfect combination of endoscopy and ultrasound technology makes the ultrasound examination in body cavity possible, so as to obtain the clear ultrasound image with very high resolution of the examined area, which makes up for part of the deficiencies of the in vitro ultrasound examination and improves the level of ultrasound diagnosis. The rapid development of transendoscopic interventional therapy in the past 20 years has greatly enhanced the concept of minimally invasive treatment and changed some of the traditional surgical concepts. With the help of many complex and ingenious therapeutic accessories, a clever gastrointestinal endoscopist can carry out minimally invasive treatments for various gastrointestinal pathologies, such as transendoscopic gastrointestinal polypectomy, submucosal tumor resection, early gastrointestinal cancer resection, gastrointestinal stricture dilatation, transendoscopic hemostasis, and endoscopic treatment of esophagogastric fundal varicose veins, etc., which can make patients need not to carry out the traditional surgical procedures, and can be performed through natural gastrointestinal treatment. The patients do not need to undergo traditional surgery, but can complete the minimally invasive treatment through the natural digestive tract, thus truly realizing the minimization of trauma and the fastest recovery. Gastrointestinal endoscopy originated from the world of magic, and after experiencing dazzling and varied rapid development, it has realized the leap from diagnosis to minimally invasive treatment. Now, it is leading us into another magical world of magic–NOTES Gastrointestinal Tumor VS Endoscopist–The New Police Story If gastrointestinal tumor is compared to a criminal, then endoscopist is a police officer without compromise. If we compare gastrointestinal tumor to a criminal, endoscopist is a police officer. Our duty is to detect the suspect with the sharp eyes of a hawk (conventional endoscopy), and to detect the suspect with the help of “tinted glasses”, “magnifying glasses”, “microscope (microendoscopy)”, “ultrasound probe”, “ultrasonic probe”, and “ultrasonography probe”. “ultrasound probe” to interrogate him, and then obtain evidence (biopsy) with the precision of a sharpshooter. However, in our hands, he can only be called a “suspect”. It is our prosecutors and judges (pathologists) who can really label him as a “criminal” and sentence him (determine the principle of treatment). The most important thing in the endoscopic management of gastrointestinal tumors is to do your job! As a police officer, no matter how confident you are in your ability to detect and handle cases, you cannot overstep your authority to convict and sentence a suspect. Our duty is to keenly identify the suspect (suspicious lesion), to grasp the complete facts of the crime as much as possible (to determine the exact extent of the lesion), and to accurately extract the evidence (biopsy tissue) and send it to the prosecutor. If it is determined to be “early stage cancer”, then we can be authorized to make an arrest (EMR or ESD). Ultimately, the suspect and all the evidence will be submitted to the judge for conviction and sentencing, and in the case of a serious crime (advanced cancer), the death penalty (surgical intervention) will be added. Diagnosis Key words: early, accurate, stereotactic localization Weapons: Conventional endoscopy Chromoendoscopy: staining, NBI, etc. Magnifying endoscopy Microendoscopy: Endocytoscopy, confocal endoscopy, etc. Ultrasound endoscopy Tips: In the face of variable gastrointestinal neoplasms, conventional endoscopy is always the most important strategic platform. On the basis of careful and conscientious routine screening, with the help of advanced weapons such as pigmentation, magnification, ultrasound and microendoscopy, tumors can be detected early and accurately, and a comprehensive diagnosis including qualitative (benign vs. malignant, early vs. late) and quantitative (extent, depth) can be made, so as to further evaluate the necessity, possibility and feasibility of endoscopic treatment. -The basic principles of endoscopic diagnosis of gastrointestinal tumors. Key words: minimally invasive, fast recovery, preservation of function Weapons (a) Endoscopic high-frequency current therapy 1. Principle of endoscopic high-frequency therapy Adopting high-frequency current of about 500kHz, using its thermal effect on the organism, it makes the local tissues warm up rapidly and causes the tissue proteins, especially the proteins in the connective tissues, to denaturation, drying, and coagulation and necrosis. When the local tissue temperature rises to more than 100℃ in about 0.1 second, it will produce gasification discharge and cut off polyps and other masses. The temperature change caused by the current through the tissue, and the cross-sectional area of the tissue section is inversely proportional to the flow of electricity through the tissue, the energization time and the resistance of the current through the tissue is proportional. 2, high-frequency current waveform cut wave, coagulation wave, mixed wave three. Cutting waveform current: a continuous sinusoidal wave, each waveform has the effective power needed to cut the tissue. It is mainly used for tissue cutting. However, the small power of the cutting wave can only make the tissue dehydration, coagulation, but can not achieve the cutting effect. Cutting waveform current cuts off the tissue quickly, but coagulation is not sufficient and bleeding is easy to occur. Coagulation waveform current: a discontinuous attenuation wave, that is, a sinusoidal waveform from the high peak voltage to the low peak voltage attenuation waveform. Its output power than the corresponding incision wave current is about 1/3 less, only part of the effective power required for incision, other less than the effective power of the waveform so that the tissue heating and coagulation, mainly used for coagulation of tissue. However, the coagulation waveform with large power can also have the function of incision. Coagulation waveform current on the tissue damage range is deep and wide, easy to cause perforation. Mixed waveform current: It is formed by the combination of attenuation wave for coagulation and non-attenuation wave for incision, and there is a proper coagulation layer formed at the same time of incision, and the ratio of incision and coagulation can be adjusted according to the specific situation, so as to achieve the best therapeutic effect and to ensure a high degree of safety. 3, high-frequency current on the effect of tissue dehydration: the current through the tissue and heat production, heat can make the tissue moisture out Cutting: when the current output power is larger, the affected tissue rapid dehydration and drying, the current resistance rises, there are ions in the surrounding air, so that the electric current can jump to the neighboring wetter tissues and produce electric sparks. Electric sparks caused by the heat than the original current through the resistance of the tissue and the heat generated by the two kinds of heat together can make the tissue cells explode, which in turn produces a cutting effect. Electrocautery: When the electrode is close to the tissue but not in contact with the tissue, the electric spark can leap from the surface of the electrode to the surface of the tissue and produce electrocautery. It initially causes coagulation of superficial tissue, followed by necrosis of deeper tissue, and ultimately the formation of a hard, black crust. The range of its wave is wider than cutting. Clinical application of high-frequency current in endoscopic treatment High-frequency current, as an external heating treatment method, has both coagulation and cutting effects, which makes it a common means of endoscopic treatment of gastrointestinal tumors, including treatment of gastrointestinal polyps, treatment of submucosal tumors, and mucosal resection of early gastrointestinal tract cancers. (Endoscopic microwave coagulation therapy (EMCT) is a kind of internal heating method using human tissues as the heat source, in which the microwave with electromagnetic wave frequency between high frequency electricity and laser acts on the local tissues of living organisms and achieves the purpose of coagulation therapy with its high temperature in a small range. Purpose. The coagulation process is slow and safe. Through coagulation, it can directly destroy the tumor as well as produce Thy-1-dependent anti-tumor immunity, which can help the treatment of tumor. Electromagnetic waves with a wavelength of 12cm and a frequency of 2,450MHz are used, and the power is generally 20W~60W, and the time required depends on the power used and the purpose of treatment. It is different from high-frequency electrocoagulation and laser photocoagulation with external heating. Microwave electrodes: puncture type – more suitable for small elevated lesions, especially submucosal tumors (which can produce wedge-shaped tissue coagulation); contact type – can produce a large range of tissue coagulation in a short period of time, suitable for low elevated lesions (e.g., shallow lesions of type IIb, IIc and III gastric cancer), due to the shallow coagulation, also suitable for the treatment of stenotic lesions. Due to shallow tissue coagulation, it is also suitable for the treatment of stenotic lesions and the prevention of postoperative stenosis. (Endoscopic laser therapy (Endoscopic laser therapy) is to make use of laser to irradiate the tissue surface of the body, which can make the tissue atoms or molecules vibrate and convert the light energy into heat energy, so that the temperature of the tissue and the cells will be increased. It is a therapeutic method that uses external heating to achieve therapeutic effects through evaporation of water from irradiated tissues, coagulation of tissue proteins, or vaporization of tissues depending on the degree of temperature increase. There are many kinds of lasers used in endoscopic laser therapy, and Nd:YAG (neodymium-doped yttrium aluminum garnet) laser is mostly used in the clinic. the wavelength of Nd:YAG laser is 1.06μm, which is the invisible light of the near infrared light, and it is highly penetrative, and it can be transmitted in a single quartz fiber optic conductor. For accurate irradiation treatment, the laser is equipped with a coaxial helium-neon laser (red light) as the aiming light. Endoscopic laser therapy is mainly used for the treatment of wide-tipped polyps of the digestive tract, inflammatory hyperplastic polyps, for the treatment of incompletely excised polyps of the digestive tract or recurrence of polypectomy, and for the relief of narrowing or obstruction of the digestive tract lumen caused by bulging tumors. The treatment of polyps is usually performed by pulsed irradiation with a power of 50-70W, lasting 0.5-1 second each time, at a distance of about 1cm. Small polyps can disappear after one irradiation treatment, while large polyps need repeated and even irradiation to achieve the therapeutic purpose. Larger ones can be treated with laser therapy in several sessions, with appropriate intervals of 3-7 days. Some patients experience abdominal distension and a burning sensation in the abdomen during treatment. The main treatment complications are perforation and pain. (D) Endoscopic argon plasma coagulation technology Endoscopic argon plasma coagulation technology (Argon plasma coagulation, APC) is actually a modification of high-frequency electrocoagulation technology. Its equipment consists of an argon source and a high-frequency power source, and the high-frequency electrodes in the argon tube of the hand-controlled system are connected to a high-frequency electric instrument (using the unipolar principle). When the high-frequency voltage reaches a certain level, the distance between the high-frequency electrode and the muscle tissue is appropriate, through the ionization of the argon gas flow and produce conductive argon and other ion beams, so that the high-frequency current can flow between the electrodes and tissues, and the thermal effect of the high-frequency current is transmitted to the corresponding tissues to produce the coagulation effect, and coagulation effect is uniform. In the coagulation process, the electrode has no direct contact with the tissue. Argon and other ion beams can not only diffuse along the electrode axial straight line, but also lateral, or even “corner” diffusion. According to the physical principle, argon and other ion beams in the application range automatically avoid the coagulated area (high impedance) and flow to the part that is still bleeding or not fully coagulated (low impedance). Thus, it automatically restricts excessive coagulation and achieves uniform coagulation effect over a large area. Its to be treated tissue from shallow and deep respectively to achieve drying, coagulation and tissue inactivation. Argon plasma coagulation technology compared with conventional high-frequency electrocoagulation methods, in the treatment of digestive tract swelling has many advantages: not direct contact with the swelling or trauma; effectively stopping large-area bleeding; continuity of coagulation, high-frequency current automatically flows to the trauma has not yet been coagulated or not completely coagulated; the depth of tissue damage is restricted to within 3mm, is not easy to lead to the perforation of thin-walled organs; argon as a protective inert gas, non-toxic and harmless to the organism; argon is a protective inert gas, non-toxic; the body is not toxic; the body is not harmful to the body, the body is not toxic. Argon is a protective inert gas, non-toxic and harmless to the body; no carbonization phenomenon, conducive to wound healing; no vaporization phenomenon, reducing the risk of digestive tract perforation; no smoke phenomenon, does not affect the line of sight. Argon plasma coagulation technology in the endoscopic treatment of digestive tract tumors in the main role: the digestive tract small or flat growth of the tissue inactivation of the swelling; swelling high-frequency electro-circuit resection of residual tissue inactivation; to the cavity growth of tumor tissue inactivation; stent placement after stenting the inactivation of the proliferative tissues (e) Mechanical ligation treatment The use of nylon or rubber laps ligation of the root of the swelling, so that the swelling ischemia, necrosis and fall off, thus achieving the removal of the swelling. (e) Mechanical ligation treatment: Nylon or rubber ligature is used to ligate the root of the swelling, causing ischemia, necrosis and detachment of the swelling, thus achieving the purpose of removing the swelling. It can be used for the treatment of large polyps with tips or the treatment of some submucosal tumors, and the former can be treated with remote high-frequency electrocautery in the ligated area after ligation. The disadvantage of this method is that a whole tumor biopsy cannot be performed. However, biopsy can still be performed at the top of the tumor after ligation. For submucosal tumors, a needle knife can be used to dissect the mucosa of the tumor after ligation, and the deep tissues can be clamped off in order to obtain a pathological basis. (F) Alcohol injection treatment: endoscopically, anhydrous alcohol should be injected around the base of the tumor, 0.5ml per point, in order to see the white mound-like elevation. Often need multiple injections to make the polyp necrosis off. It can be used for the treatment of broad-based polyps. (G) Liquid nitrogen cryotherapy has been used for polyp treatment under rigid proctoscope. The treatment process will show steam and affect observation, and is difficult to apply under fiberoptic endoscopy or electronic endoscopy. Strategy Endoscopic treatment options for gastrointestinal tumors: For gastrointestinal tumors, endoscopic treatment can be based on the nature of the tumor and its growth pattern and other conditions, such as endoscopic resection, coagulation, ligation, injection or freezing, or the combined application of a variety of therapeutic modalities in order to achieve the desired therapeutic effect. Resection is mainly performed by high-frequency electric laparotomy, which can also be combined with the application of high-frequency electric needle knife resection. There are various methods of coagulation, commonly used high-frequency electrocoagulation, including single-electrode high-frequency electrocoagulation, double-electrode high-frequency electrocoagulation and argon plasma coagulation with the application of argon, and microwave coagulation or laser coagulation technology can also be used. (I) Endoscopic treatment of gastrointestinal polyps The presence of gastrointestinal polyps may lead to bleeding and other complications, and larger polyps may also cause gastrointestinal obstruction, and in severe cases, malignant changes may occur. Therefore, in principle, all gastrointestinal polyps should be treated. Endoscopic treatment has become the first choice of treatment, and the whole tumor biopsy can also clarify the nature of the polyp. In general, most polyps can be treated endoscopically as long as there are no contraindications to endoscopy. The so-called contraindications are often relative, with the continuous improvement of endoscopic technology and treatment methods, has greatly expanded the scope of endoscopic treatment of polyps. Specifically according to the endoscopist’s technical level, endoscopy room supporting conditions, the nature and size of the polyp, the patient’s physical condition, etc., in order to avoid the occurrence of complications. 1.Tip digestive polyps For the tip of the digestive tract polyps, generally can be used high-frequency electric coil sleeve resection. The position of the trap should try to cover the tip of the near-polyp part, as long as possible to retain the length of the residual tip, in order to improve safety and prevent perforation. The stalk of the polyp is in fact the normal gastrointestinal mucosa pulled by the polyp, rather than tumor tissue, after polyp excision, the residual tip can gradually retract, until it disappears. The retention of the long stump is also conducive to the treatment of immediate postoperative hemorrhage, when the stump can be easily coagulated with a ring sleeve and then electrocoagulated to achieve coagulation and hemostasis, and if necessary, titanium clips can be used to close the root of the stump in order to achieve better hemostatic effect. Mixed currents are often used for treatment, and the power varies according to the type of high-frequency electrical generator. Mixed incision current and coagulation current ratio is often 2:1, according to the size of the polyp, stipe thickness, coil wire pulling resistance and other factors and make corresponding adjustments. Often use the coagulation current first, and then use the mixed current for cutting. For thick polyps, or for polyp segmental resection, repeated application of mixed current and coagulation current in order to make the cutting site to get sufficient coagulation, to avoid bleeding. For small, long-tipped polyps, coagulation current alone is sufficient for excision. Slowly tighten and pull the wire after encircling the tip of the polyp. Be careful not to over-tighten and pull the wire to cause mechanical cutting and bleeding. When the loop is adjusted to the appropriate position and the appropriate degree of tightness, gently lift the loop device, so that the polyp away from the intestinal wall and suspended in the intestinal lumen of the instantaneous electric coagulation or cutting. Before energizing, it should also be ensured that the coil wire, especially the end of the wire does not touch the intestinal wall. Due to the size of the polyp, growth location and intestinal peristalsis and other factors, the suspension of the polyp is often short-lived, or even difficult, the treatment should grasp the timing of the energization, and pay attention to the timely disconnection of electricity, so as not to burn the intestinal wall, or even cause perforation. For too large polyps, it is not possible to realize the complete suspension and electro resection, should try to increase the contact surface of the polyp and the intestinal wall, so that the amount of current per unit area through here to avoid the intestinal wall of the burns, but still should be made to the trap part of the suspension in order to make the temperature of the highest temperature here and achieve the therapeutic purpose. If the head is too large for the trap to fit completely, the segmental resection method can be used. The head of the polyp is first subdivided for electrodesiccation, and only at the end is the residual polyp fully enucleated and resected. The head of the subdivided excision should be appropriate to increase the intensity of coagulation, in order to prevent bleeding. Nylon rope can also be used to tie the tip of the polyp in order to block its blood flow, and then the polyp subdivided excision, in order to reduce the risk of postoperative bleeding. 2, non-tibial gastrointestinal micro-polyps For non-tibial gastrointestinal micro-polyps, the trap is often more difficult, or easy to mechanical cut and cause bleeding. For such polyps, the application of thermal biopsy cauterization is the ideal treatment method, on the one hand, the ideal removal of small polyps, on the other hand, easy to send the excised tissue for examination and obtain pathological information. For multiple small polyps, can be unipolar or bipolar electrocoagulation cauterization, or even slightly outstretched with a thermal biopsy head coil wire gently touch the polyp after electrification for electrocoagulation, the conditions of the application of argon plasma coagulation technology is more effective, better safety. 3, small polyps of the gastrointestinal tract for the diameter of about 0.5-2.0cm of the gastrointestinal tract polyps, is still the main choice of high-frequency electrolysis of the trap method of treatment. Suction of air in the digestive tract before the trap, so that the digestive tract wall relaxation, and the use of the digestive tract peristalsis polyps to the cavity of the timing of the polyp base of the polyp slightly above the set of polyps, to the digestive lumen to gently lift the polyp, the first coagulation and then cut the polyp with a mixed electric current. Be careful not to put the normal tissue near the polyp into the trap, and be careful not to over-coagulate, so as not to burn the wall of the digestive tract, or even cause perforation. For relatively large non-tibial polyps, if necessary, can be considered for submucosal injection in order to make the polyp bulge before the trap electric resection (endoscopic mucosal resection approach), in order to reduce the gastrointestinal tract intrinsic muscle layer of the electric burn, reduce the gastrointestinal tract perforation and other complications. 4, non-tibial digestive tract polyps For diameter greater than 2cm of the digestive tract non-tibial polyps, endoscopic treatment caused by bleeding and perforation of the risk is higher, should be careful to operate, choose a reasonable treatment method. For large non-tibial polyps with a narrow base, high-frequency electric coil resection can still be carefully selected. The removal of such polyps, should ensure adequate electrocoagulation to avoid bleeding, and should be careful not to electrocoagulate too deep and damage the normal wall of the digestive tract, how to grasp the degree of the two is to ensure the safety of the treatment of the key. For the wider base and lateral growth of polyps, commonly used endoscopic mucorectomy (Endoscopic mucoresectomy, EMR) method, can be used with hypertonic saline or 1/10000 epinephrine saline for polyp base submucosal injections, so that the base of the polyp bulge, and then use the ring sleeve to cover the bulge of the lesion after high-frequency electrodesiccation, the lesion is too large can be divided into pieces of the excision. The addition of a little methylene blue to the submucosal injection solution can make the submucosal layer appear light blue, which is beneficial to the assessment of the trauma after the lesion mucosal excision. If a light blue trauma can be seen after electrosurgery, it means that the section of electrosurgery is just in the submucosal layer, which achieves the goal of complete removal of the polyp without removing it too deeply and damaging the muscularis propria, or even perforating it. Utilizing a barbed circler may make circling treatment easier. Using a double-lumen endoscope, the difficulty of trapping is reduced by applying the trap around the lesion and then lifting the lesion with grasping forceps from the other endoscopic cavity. For residual polyps, coagulation and inactivation of residual tissue can be performed with argon plasma coagulation. When making mucosal resection, mostly choose pure cutting current to reduce the electrocoagulation injury to the muscle layer. (II) Endoscopic treatment of submucosal tumors For submucosal tumors, endoscopic treatment should be preceded by endoscopic ultrasonography in order to clarify the level of the digestive tract wall where the tumor is located and initially estimate the nature of the tumor. For the lesions in the mucosal layer and submucosal layer, such as smooth muscle tumors, mesenchymal tumors, lipomas, etc., endoscopic treatment can be carried out if the tumors are not too large. For mesenchymal tumors of the intrinsic muscle layer, endoscopic treatment has also been successful, but the chance of perforation is greater, so caution should be exercised. For submucosal tumors, if the tumor is not big and grows into the cavity, a trap can be used to directly set to the bottom of the tumor, so that the tumor can be protruded and pulled into the cavity, and then electrified for high-frequency electrodesiccation. Be careful not to overcoagulate and incur perforation. For relatively flat submucosal tumors, submucosal injection can be used to separate the mucosal layer from the intrinsic muscle layer, and with the help of a transparent cap with a groove installed at the endoscopic end, the tumor can be suctioned to the cap for high-frequency electrodesiccation with the help of negative pressure. Before the negative pressure suction, the loopers are coiled around the inner groove of the transparent cap, and when the suction is appropriate, the loopers are pulled back and the outer tube of the loopers is pushed forward to completely encircle the tumor, similar to the operation of esophageal variceal vein ligation with a nylon rope. Although the submucosal injection before trapping can reduce postoperative bleeding and prevent excessive damage to the gastrointestinal wall, the mucosal elevation after injection often affects the localization of the submucosal tumor, which should be fully estimated before injection, and if necessary, an appropriate way can be chosen to localize the tumor before injection. For the cases of submucosal tumors with unsatisfactory exposure of lesion site and difficult to perform endoscopic mucosal resection, such as those with tumor diameter within 1.0cm, the method of esophageal varices ligation can be used, using rubber or nylon ring for ligation, and the tumor body will be necrotic and detached to achieve the therapeutic effect after the ligation. If necessary, the tumor can be dissected by needle knife after ligation and deep biopsy can be done to get the basis of pathological diagnosis. For submucosal tumors that are large in size and difficult to be resected by endoscopy alone, Hybrid NOTES can be performed with laparoscopy – a two-pronged approach, which can be combined with laparoscopy. (C) Endoscopic treatment of precancerous lesions For precancerous lesions such as severe atypical hyperplastic lesions and flat elevated adenomas, if the lesions are more limited, endoscopic mucosal resection can be performed as described above. The resected tissue should be sent to pathology for examination in one piece, and attention should be paid to the edges of the resected material to assist in determining whether the resection of the lesion is complete or not. (IV) Endoscopic treatment of early gastrointestinal tract cancer For early mucosal layer cancer without obvious ulcers or ulcer scars on the lesion surface, endoscopic mucosal resection (EMR) can mostly achieve complete resection. For intramucosal cancers whose tumor cells are confined to the glandular basement membrane (intraepithelial) or the mucosal lamina propria (intramucosal), and have not passed through the mucosal muscular layer to reach the submucosal layer, endoscopic mucosal resection can also be performed at the lesion site. If the scope of lesion is large, or the patient cannot tolerate surgery, endoscopic multiple partial resection (EPMR) can be performed, and the treatment should be completed within 2 weeks to avoid the formation of surgical scar, which will affect the effect of resection again. The endoscopic submucosal dissection (ESD) developed in recent years can achieve the purpose of one-time bulk resection of endomucosal cancer, which ensures the integrity of the excised specimen and facilitates the evaluation of whether the lesion is completely resected or not. In order to achieve complete endoscopic resection, the size of the lesion and the depth of infiltration should be accurately estimated preoperatively (with the help of ultrasonic endoscopy), and attention should be paid to the presence of multiple cancer foci. Staining with methylene blue and indigo carmine staining solutions can help to determine the extent of the lesion, and the identification of the lesion can be improved with magnified endoscopic observation. The advent of endoscopic narrow-band imaging or spectroscopic techniques has facilitated the visualization and identification of lesions. In order to determine whether the lesion is completely excised and the depth of lesion infiltration, the cut specimen should be sent for histologic examination after the whole piece of the cut specimen is flat and fixed, and the specimen should be examined by continuous sectioning every 2 mm. Miyazaki, a Japanese expert, put forward the judgment criteria for determining the absence of cancer cells in endoscopically resected mucosal specimens: ① no cancer cells were seen at the edge of each section; ② the length of any slice should be greater than the length of the cancer in the adjacent section; ③ the edge of the cancerous foci from the end of the resected specimen should be 1.4mm in the case of highly differentiated ductal adenocarcinomas and 2mm in the case of moderately differentiated ductal adenocarcinomas. It is generally considered that the shortest distance between the edge of the cancerous foci and the end of the resected specimen should be Generally speaking, it is considered that the shortest distance between the edge of cancerous lesion and the resection tip is ≥2mm (equivalent to more than 10 normal glandular ducts) as complete resection; the shortest distance between the edge of cancerous lesion and the resection tip is ≤2mm as incomplete resection, and endoscopic resection can be performed again for highly differentiated adenocarcinoma, while surgical operation should be carried out for poorly differentiated adenocarcinoma; and when there are still cancerous cells at the resection tip, it is considered as residual resection, and additional surgical operation is needed. In addition, for those whose pathological examination suggests that there is infiltration of submucosal layer, additional surgical treatment should be performed. After endoscopic treatment of digestive tract tumors, the resected tissue specimens should be taken out as much as possible for pathological and histological examination to further define the nature of the tumor. After endoscopic treatment of gastrointestinal tumors, specimens should be removed as much as possible for histopathologic examination to further define the nature of the tumor. Micro-polyps should be removed by thermal biopsy after cauterization. For similar multiple micro-polyps, only 1-2 specimens were taken for examination. Separate specimens for different types and sites are appropriate. For small polyps resected with a loop, if the wire can be retracted into the outer casing after resection, the specimen can be obtained after pulling out the loop and sent for examination. After resection of larger polyps or submucosal tumors, the specimen can be pulled close to the endoscopic end of the endoscope and withdrawn from the gastrointestinal tract together with the endoscope by using a trap or grasping forceps. If mucosal resection is performed with the help of a transparent cap, the resected tissue can be sucked into the transparent cap after surgery and then withdrawn from the endoscope to obtain the specimen. The specimen is usually soaked in formalin solution and then sent for examination, and special treatment is required for special examination. Complications of endoscopic treatment of gastrointestinal tumors and their treatment Complications of endoscopic treatment of gastrointestinal tumors mainly include bleeding and perforation. Attention should be paid to not resecting too deep, coagulating too much, and exhausting the gas in the digestive cavity as much as possible after operation to reduce the occurrence of perforation. For traumatic blood seepage, electrocoagulation can be used, especially argon plasma coagulation effect is better, and bipolar electrocoagulation is better than unipolar electrocoagulation. For the blood seepage from the stump of the pedunculated polyp, a trap can be used to cover the stump and then electrocoagulate, which is more effective. For jets of bleeding from larger vessels, hemostatic clips should be used, and hemostasis is more desirable. When perforation occurs, the application of multiple titanium clips or combined Endoloop on the perforation site and its surrounding “suture” treatment, most can avoid surgery.