According to statistics, among colorectal cancer patients, some of them have reached advanced stage at the time of initial diagnosis, and the surgical resection rate is 50%-70%, and nearly 80% of them do not see residual lesions during and after surgery, but 40%-70% of them still have tumor recurrence and metastasis. Nowadays, with the improvement of treatment, the median survival has increased to 20-30 months. How to achieve longer survival is a common concern for patients and doctors. From the general treatment routine of solid tumors, systemic drug therapy is the main treatment for advanced tumors. At present, internationally recognized drugs that are effective for advanced colorectal cancer include four chemotherapeutic drugs
(5-Fu, capecitabine, oxaliplatin, irinotecan) and two monoclonal antibodies (anti-VEGF monoclonal antibody and anti-EGFR monoclonal antibody), and from the level of drug treatment alone, as long as the three types of four chemotherapeutic drugs are used well, patients can basically obtain a median survival of more than 20 months. The second monoclonal antibody is also very effective in increasing tumor control rate and prolonging survival, and the median survival obtained from some clinical trials containing these drugs has exceeded 20 months or even 30 months. In the absence of more effective drugs on the market, it is unlikely that longer survival can be achieved by drug therapy. Clinical observation shows that liver metastasis of colorectal cancer has its special features: 1. High incidence, 20% of patients have liver metastasis at the time of consultation, 50% of patients will have liver metastasis after surgery, and liver metastasis can be found in 70% of dead patients at autopsy. 2.The liver is the only organ with metastases in a significant proportion of patients, and extrahepatic metastases do not appear in a longer period of time. 3. Clinical practice shows that 22% to 58% of patients whose liver metastases are completely removed can survive for more than 5 years. Even if the tumor cannot be removed by the original surgery, 30% of the patients can still survive for more than five years if the tumor is reduced in size by drug treatment and then removed. Based on these characteristics, aggressive treatment of liver metastases can significantly extend patient survival. This is also a breakthrough to improve the survival of colorectal cancer patients before new drugs become available. At present, the main non-pharmaceutical treatments for liver metastases are as follows: 1.Surgical resection, which is a traditional treatment method with undoubted effectiveness, but has many shortcomings, such as large trauma, impossibility of multiple operations for recurrent lesions, more damage to normal liver tissues, and difficulty in dealing with hilar and paravalvular lesions. 2.Ablation therapy, including chemical ablation (intra-tumor anhydrous ethanol injection, etc.) and physical ablation (radiofrequency therapy and argon helium knife), has the advantages of less trauma, repeatable treatment, precise efficacy, less damage to normal liver tissues, and higher safety for treatment of hilar and paravalvular lesions, but it is difficult to completely inactivate tumors with a diameter of 3 to 5 centimeters or more. 3. Radiation therapy has better safety, but it has the advantages of radiation damage, easy to develop radiation enteritis and hepatitis, and incomplete tumor killing when the dose is insufficient. Among the above treatments, ablation therapy (such as radiofrequency, anhydrous alcohol intratumoral injection, etc.) is the most suitable means for repeated use without obvious side effects. With the help of artificial pleural fluid and ascites-assisted ultrasound guidance, our treatment targets have been basically re-covered to every part of the whole liver, eliminating the blind area of treatment and providing patients without surgical indications (repeated surgery, tumor adjacent to large blood vessels, large number of tumors and wide distribution, etc.) with the possibility of completely eliminating liver metastases and prolonging patients’ survival.