Colorectal cancer seriously endangers people’s health. The conventional treatment method for colorectal cancer is surgery, but with the development of endoscopic technology, there are many minimally invasive means to effectively treat colorectal cancer.
1.Laser treatment
Laser therapy mainly uses the feature of easy focusing of laser to gather laser light on a small area, so that the irradiated local tissues absorb light energy and generate high temperature, protein coagulation and water vaporization of tumor. However, because the penetration depth of this laser is about 4mm, the depth is difficult to control, the cauterization range is small, the thermal damage is large, and it has the characteristics of tissue selective absorption, it is difficult to operate precisely and easy to cause perforation, so it is less used in the clinic.
2.Microwave therapy
Microwave can cause rapid electric field changes in the tissue water molecules rotational movement, causing the tissue itself to heat up. The degree of microwave-induced tissue heating is much less than that of laser, generally not more than 100 ℃, safer than laser. However, microwave therapy to make the lesion within the tissue to reach the required temperature at the same time, but also to ensure that the maximum normal tissue is not damaged by heat, for the operation of high technical requirements, excessive cautery prone to intestinal perforation and other serious complications, while the treatment wire easy to heat easily damaged endoscopy. At present, it is also less used in the clinic.
3, argon ion coagulation
Argon ion coagulation is a non-contact electrocoagulation device, which transmits high frequency electrical energy to the tissue through ion gas (argon ion beam).APC is suitable for: inactivation of tissues at partially adherent tumors or tumors close to the canal wall, inactivation of granulation tissues (tumor proliferation) after inward growth of tumor tissues or stent placement, inactivation or hemostasis of adenoma metastases or residual tissues after EMR (ESD) treatment.
Compared with conventional methods, APC has the following advantages.
①No contact with the wound surface and no tissue adhesions;
②Low blood loss, especially for parenchymal tissues;
③Continuous coagulation, high-frequency current automatically flows to the uncoagulated or incompletely coagulated wound tissue, and the depth of damage is limited to 3 mm, which will not lead to perforation of thin-walled organs;
④Argon is an inert gas, non-toxic and harmless to the body, no charring phenomenon, which is conducive to wound healing;
⑤No vaporization phenomenon, the risk of perforation is smaller;
⑥No smoke phenomenon, good line of sight, no odor interference;
⑦ Easy to operate, short operation time.
Disadvantages of APC.
①The treatment depth is shallow;
②There may be lesion residue causing lesion recurrence.
4.Freezing method
Cryotherapy is to insert the cryoprobe into the target tissue or apply the chillogen directly to the target tissue to lower the local temperature to below the critical level (-40℃) and produce ice outside and inside the cell, or form soluble crystals, or destroy the blood vessels inside (or adjacent to) the target tissue to affect or cut off the nutrient and oxygen supply to the tumor, so as to achieve the purpose of destroying the tumor tissue. It is suitable for the radical treatment of early stage cancer near rectum and anal canal or the palliative treatment of progressive stage. However, cryotherapy may leave tumor cells at the edge of the frozen area, which increases the possibility of recurrence, and the frozen area is too large, which may cause serious complications such as organ dehiscence and “cold shock”. In addition, the indications for cryotherapy are narrow, which are those who cannot be treated surgically for various reasons, and the upper edge of rectal tumor is within 8 cm from the anal verge, the size of the tumor does not exceed 1/2 circumference of the intestinal wall, and the pathology is highly differentiated adenocarcinoma. Cryo device is also required.
5.Radiofrequency treatment
Radiofrequency mainly uses the thermal effect in biophysics to play a therapeutic role. Radiofrequency current conducts current through high frequency oscillation and ionic vibration, and transforms ohmic depletion into heat energy to dehydrate, dry and coagulate necrosis of tissues, so as to achieve the treatment purpose. Radiofrequency electrode can cauterize the point or surface of augmented lesion in multiple angles and directions, independent of the shape of augmented lesion and basal width, and can be carried out continuously to cause necrosis and detachment of tumor material. However, its prolonged cautery in the tumor may cause some tissues to adhere to the RF head, which may cause serious bleeding in the deep part of the tumor tissue when pulling out the RF head, so it is not widely used in the clinic at present.
6.Endoscopic mucosal resection
As a method to treat polyps, precancerous lesions and early cancers, endoscopic mucosal resection is widely used in clinical practice because of its easy operation, short operation time, high safety and few complications. Due to the limitation of EMR operation procedure, the lesion range for each EMR treatment is generally less than 2 cm in diameter. if it exceeds a certain range, a modified staged endoscopic mucosal resection treatment is required. In contrast, EPMR treatment may cause an increase in cancer recurrence rate due to factors such as residual lesions. However, EMR is still worth promoting as one of the minimally invasive treatment methods for early colorectal cancer as long as the indications are strictly mastered, the operation is standardized, and the regular follow-up after treatment is done. Of course, if the lesion diameter is 2~3 cm, endoscopic submucosal dissection can be used first to excise the lesion completely, and then EMR trap can be used to excise the lesion at one time. This combination of EMR trap and ESD can reduce the treatment time and complications while ensuring the integrity of lesion excision and obtaining satisfactory tissue specimens, thus reducing lesion residue and recurrence.
7.Endoscopic submucosal dissection
Endoscopic submucosal dissection is a technique for circumferential resection and dissection of early gastrointestinal tumors based on EMR using special endoscopic instruments and other auxiliary equipment. Theoretically, ESD can completely resect early cancer lesions of any size, shape, and with or without ulcers, and the depth of resection can include the whole mucosa, the mucosal muscle layer and most of the submucosa layer, and the whole resection can reduce the residual lesions and cancer recurrence and achieve the purpose of radical resection of early colorectal cancer. The indications for ES D are still controversial, and the main complications of ES D are bleeding and perforation. The incidence of perforation is higher than that of EMR, ranging from 1.4% to 10.4%.
Unfortunately, the standardization and safety of colorectal ESD performed by general practitioners has not yet been established because of the following reasons.
(i) Colon ESD is difficult to perform, and the thin wall, peristalsis, folds and intestinal feces can affect the ESD operation;
②If the intestinal wall is perforated, peritonitis due to fecal leakage will require emergency surgical treatment. Therefore, although ESD can avoid unnecessary open surgery for patients with colorectal tumors by complete resection of the lesion at one time. However, at present, colorectal ESD is in the developmental stage, and the corresponding indications need to be determined through clinical practice according to the nature and location of the lesion, the proficiency of the operating surgeon, the time required for ESD, and the equipment conditions of the hospital where it is performed. Clinical applications (studies) regarding colonic ESD should be carried out with caution. Inexperienced and untrained colonoscopists should not perform ESD alone.
8. Topical chemotherapy drug therapy
Endoscopic implantation of chemotherapy slow-release ions into colorectal tumor tissues and peritumor interstitial tissues can increase the concentration of drugs at the tumor site, prolong the duration of drug action with cancer cells, reduce systemic toxic reactions, and better play the role of local control of tumor. The literature reports that the efficacy of conventional intravenous or oral chemotherapy for gastrointestinal malignant tumors is 30% to 40%, and the incidence of toxic reactions is 25%. In contrast, endoscopic implantation of chemotherapeutic delayed-release particles at the tumor site has been shown to have an average efficacy of 73% for targeted therapy. The only adverse effects, except for intraoperative bleeding, were mild decrease in white blood cells, mild malignancy, diarrhea, and no impairment of liver or kidney function. It can be used as palliative treatment for patients with advanced colorectal tumors, recurrent cases or inoperable patients.
9.Stent placement
Endoscopic stenting of colonic cancerous obstruction is one of the palliative methods to treat malignant obstruction of the colon or rectum by endoscopically guided placement of metal stents under X-ray fluoroscopy. Generally endoprosthesis is performed mainly for left hemicolectomy or rectal obstruction, but for obstruction in the transverse colon, or even near the liver area, it is sometimes possible to release it successfully using a specially designed stent. The success rate of stent placement is about 85-100%, and colonic decompression can be achieved immediately after surgery in 75-100% of cases.
The advantages are.
(i) improvement of the patient’s general condition by alleviating possible water-electrolyte disturbances;
②Improve the intracolonic environment through decompression and cleansing effect, which facilitates subsequent stage I resection and anastomosis;
(iii) facilitating the performance of preoperative examinations, such as barium meal, colonoscopy, CT, etc., to assess the possibility of resection and the presence of distant metastatic dissemination.
It is mainly suitable for.
①Patients with advanced age and advanced distant metastasis of tumor that cannot be treated surgically, which can relieve patients’ obstructive symptoms in the shortest time and most effectively;
②It can change acute intestinal obstruction patients from emergency surgical treatment to elective surgical treatment, and improve the success rate and safety of surgical stage I radical surgery. The mortality rate of surgery can be reduced from 17% to 7.7%. Serious complications occur at a rate of about 1%, including colonic perforation and sepsis, sometimes requiring emergency surgery. Long-term complications include stent migration and stent obstruction. Intraluminal metal mesh stents for local treatment with radiotherapy and chemotherapy particles are available, but have not yet been used in clinical practice.