Colorectal cancer is one of the most common malignant tumors in human beings. In China and the world, colorectal cancer is the third most common cancer. In Shanghai, colorectal cancer is second only to lung cancer among male citizens and second only to breast cancer among women. According to the statistics of Shanghai Cancer Institute, the number of colorectal cancer cases in Shanghai has doubled in the past 20 years: 1,546 new cases of colorectal cancer in Shanghai in 1986 and 3,290 new cases in 2006. The most common site of metastasis for colorectal cancer is the liver. About 25% of patients have metastatic lesions in the liver when they are diagnosed with colorectal cancer; 35-55% of colorectal cancer patients will have liver metastases sooner or later, and 2/3 of them eventually die from liver metastases. According to the American Cancer Society, in 2009, there were 146,970 new patients with colorectal cancer, 75,000 patients with liver metastases, and 49,920 deaths from colorectal cancer in the United States. The treatment of liver metastases from colorectal cancer remains a perplexing and challenging issue to date. Data show that the median survival of colorectal cancer patients with combined liver metastases is only 6-12 months without treatment, 12-24 months with unresected chemotherapy, and 35-58 months with radical resection of the metastases. Radical surgical resection is the main way for patients to obtain the so-called “curative treatment”. Data from the last decade show that the 5-year survival rate of patients with resected liver metastases is nearly 60%, while the 5-year survival rate of patients who do not or cannot be resected is 0-5%. Therefore, the outcome is very different with or without surgical resection. Other curative treatments include “ablation” (or “destruction”), i.e., the complete destruction of intrahepatic lesions by radiofrequency, freezing, microwave, etc. With the advancement of liver surgery technology, the location of metastatic tumors in the liver is no longer a concern for liver surgeons. The question that hepatic surgeons consider is whether all tumors can be completely destroyed (resected or ablated) in one or several stages. Will the volume and function of the remaining liver be sufficient after surgery? Therefore, all patients in whom metastases are potentially resectable are patients with indications for surgery, either in a single pass or in a fraction of a pass, unless there are contraindications to surgery. The principle of surgical resection is that the volume of the residual liver is functionally sufficient to sustain the patient. In general, 30% of the normal liver should be sufficient, while 40% of the liver with liver injury (e.g., after high-dose chemotherapy) must be preserved, and in some cases of cirrhosis: 40-50% . Of course, liver volume is not a complete reflection of liver function reserve, and other tests are usually needed to get a more complete picture of liver function reserve. What is “radical resection”? It has been suggested that a radical resection is only when the margin is 1 cm or more from the tumor margin. In other words, a 1-cm margin is necessary. Subsequent studies have found that “microscopically negative margins”, i.e., no cancer cells at the microscopic margin, is the key to prognosis, and the width of the margin is not related to recurrence or survival. Without tumor residue (i.e. R0 resection), the median survival of patients was 46 months, and with tumor residue, the median survival was 24 months, which was a significant difference. Significance of intraoperative ultrasound Intraoperative ultrasound is the application of ultrasound to explore the liver during surgery. Its sensitivity is higher than all current preoperative imaging examinations. The application of a high-resolution probe can detect microscopic lesions of 3-4 mm in the liver and can accurately assess the relationship between the lesion and important structures of the blood vessels and bile ducts, which has an important impact on intraoperative decision making. 10-12% of cases can detect at least one lesion that was not detected preoperatively; 68% of surgical plans need to be changed after the use of intraoperative ultrasound. Currently, one of our routine steps is to do intraoperative liver ultrasound after surgical opening of the abdominal cavity. Significance of chemotherapy in the treatment of liver metastases from colorectal cancer In recent years, chemoradiotherapy has assumed an increasingly important role in the treatment of liver metastases from colorectal cancer. Several large-scale clinical trials have confirmed that some unresectable intrahepatic metastases (about 10-20% of patients) have been reduced to resectable lesions after chemotherapy, and the results after resection are similar to those of patients with resectable metastases; some resectable intrahepatic metastases are first treated with chemotherapy and then resected, which can reduce the chance of local recurrence and prolong the survival of patients; post-resection chemotherapy is also a common method in the treatment of liver metastases. Chemotherapy after resection is also a common method in the treatment of liver metastases, aiming to control local recurrence and prolong patient survival. Chemotherapy is also an independent predictor of long-term survival. The 5-year survival rate after surgical resection of intrahepatic metastases is higher in patients with effective chemotherapy (37%) than in patients with ineffective chemotherapy (8%). Some patients with intrahepatic lesions after chemotherapy are seen to shrink significantly or even disappear completely by CT and other examinations. Doctors usually pursue the tumor shrinkage, originally unresectable become resectable, not the disappearance of the tumor. Even if the lesions are no longer visible, only a very small percentage (<4%) of the tumor cells in the metastases are completely killed. Most patients may have tumor cells in the original lesions coming back despite the fact that the tumor is no longer visible in the liver on CT or other imaging examinations. On the other hand, once CT, PET or intraoperative ultrasound is difficult to detect the lesion, it will be very difficult for surgeons to remove the tumor accurately and increase the possibility of recurrence after surgery. Moreover, in order to achieve the "disappearance" of tumor, excessive chemotherapy is often needed, which will undoubtedly increase the damage of chemotherapy drugs to the liver, and if surgery is still needed in the future, the risk of surgery will increase, and the complication rate of surgery may increase. Therefore, if chemotherapy is effective and the tumor shrinks to the extent that it can be removed, surgery should be chosen at once. Molecular targeted therapy Molecular targeted therapy is to target the important molecules related to the growth and proliferation of tumor cells, and to deliver a powerful targeted attack, so as to block the growth and proliferation of tumor, or to induce apoptosis of tumor cells. Commonly used targeted drugs for colorectal cancer include: i. Bevacizamab (Avastin), a recombinant humanized anti-VEGF antibody, was approved by FDA on December 26, 2004, and is used in combination with chemotherapy as the first-line drug to increase pathological remission rate and reduce tumor cell activity. Its half-life is 20 days (11~50 days). If the drug is used before surgery, surgery should only be performed 6~8 weeks after the last dose, otherwise bleeding, fistula, non-healing incision, and obstructed liver regeneration can easily occur. Second, Cetuximab (Cetuximab, Erbitux Epidermol), Third, Panitumumab (Panitumumab, Vectibix Vectibix), EGFR antibody, inhibits tumor cell proliferation, migration and promotes apoptosis of cancer cells. Resuscitation therapy Some patients who are resistant to chemotherapy and whose usual chemotherapy regimens are ineffective may benefit from the addition of targeted therapies such as Epiduo, which is called salvage therapy. About 7% of the patients who were originally ineffective in chemotherapy had their tumors shrink after salvage treatment and achieved the purpose of resection. Batch resection of liver metastases (sequential resection) Multiple metastases in the liver that cannot be removed in one operation can be resected in batches. This is usually done by preoperative chemotherapy followed by elective complete resection (or combined with radiofrequency ablation) of the left hepatic lesion, along with embolization or ligation of the right hepatic portal vein (PVE or PVL), or simultaneous separation of the liver parenchyma of the right and left hepatic halves (ALPPS), the purpose of these measures being to induce hyperplasia of the contralateral liver (left liver). The volume of the portion of the liver that is desired to be preserved (FLR) can usually increase significantly after 1-4 weeks, at which time the right half of the liver containing the tumor is removed. The value of radiofrequency ablation (RFA) RFA is usually used in combination with surgery as a complement to surgical resection, and radiofrequency ablation increases the number of surgical resectors, but should not completely replace surgical resection. The recurrence rate after RFA alone is higher than that of surgical resection, so the overall prognosis is better if resection is possible than relying on RFA alone . Management of colorectal cancer with concurrent liver metastases About 15-25% of patients with colorectal cancer have concurrent liver metastases at the time of obtaining the diagnosis, among which, about 30% of patients can have both the primary site (i.e. colorectal cancer) and liver metastases resected. The traditional management is a staged surgery: colorectal cancer resection 2 to 3 months later Liver resection. Newly, many doctors choose to do simultaneous resection for patients, that is, to do two parts of resection in one operation, thinking that it is safe and avoid patients to suffer from two operations. However, simultaneous surgery is more traumatic after all, and the decision of whether it is better to operate in separate operations or in the same period should be individualized, taking into account the extent of liver metastases, the size of the resected liver, and the experience of the surgeon. The management of patients with extrahepatic metastases It has always been considered that the combination of liver metastases and extrahepatic metastases from colorectal cancer is a sign of poor prognosis and an absolute contraindication to surgery. However, in recent years, aggressive surgical treatment, i.e. hepatic resection combined with resection of extrahepatic metastases, has been increasingly adopted for such patients. If complete resection of all metastases inside and outside the liver (R0 resection) can be achieved, the long-term survival rate (29%) is similar to that of patients with liver metastases only without extrahepatic metastases undergoing hepatic resection (38%, p=0.072). The key is the ability to achieve resection of all metastases without residuals. The 3-year survival rate for patients without complete and residual resection (R1) was significantly lower (24%) than for patients with complete resection (R0) (45%). Several large series involving combined resection of extrahepatic metastases have been reported in the last 20 years, with 5-year survival rates ranging from 20-28%, which is difficult to achieve in patients without resection. Case A, a male farmer from Jiangsu province, was diagnosed with descending colon cancer in May 2002 (then 34 years old) and underwent radical resection of the left hemicolectomy in a local hospital, followed by 6 courses of postoperative chemotherapy. In October 2004, he came to our hospital for consultation because of the increasing distension and pain in the upper abdomen. On October 4, 2004, he underwent right hepatectomy combined with retroperitoneal metastasis resection in our hospital without any postoperative treatment. Case B, male, from Shanghai. He was diagnosed with rectal cancer on May 10, 2005 (aged 50 years at that time). He underwent radical rectal cancer surgery (Dixon operation) in our hospital and postoperative chemotherapy. he was diagnosed with metastatic liver cancer on December 5, 2005 and underwent partial hepatectomy. right lung metastasis was found in April 2008 and lobectomy was performed on April 22, 2008. She has survived for more than 9 years. Case C, female, from Shanghai. April 13, 2007 (then 64 years old). She was diagnosed with ascending colon cancer combined with simultaneous liver metastasis, and underwent right hemicolectomy at Fudan University Cancer Hospital on April 18, 2007, followed by 2 courses of postoperative chemotherapy (oxaliplatin + siroda), and the metastases in the liver were significantly reduced. He is now alive for 7.5 years. Case D, male, 57 years old, from Shanghai, was diagnosed with rectal cancer in August 2008 and underwent radiotherapy and chemotherapy for 3 months. CT showed 7 intrahepatic lesions, one of which was 3 cm in diameter and located in the second hepatic hilar, in the angle between the root of the middle hepatic vein and the inferior vena cava, and hepatectomy was performed on August 25, 2009. On December 9, 2009, a recurrent lesion was found in the right lobe of the liver, with a diameter of about 1.5 cm, and radiofrequency ablation (RFA) under ultrasound guidance was performed on December 24 of the same year.