Primary liver cancer (hepatocellular carcinoma) is one of the common malignant tumors in China, and China currently accounts for about 55% of the global incidence and about 110,000 deaths from liver cancer each year, accounting for 45% of the mortality rate of liver cancer worldwide. It ranks second after lung cancer in terms of tumor-related deaths [1]. The existing treatments for liver cancer mainly include surgical resection (hepatectomy, liver transplantation and palliative surgery) and non-surgical treatments (ablative therapy, arterial chemoembolization, molecular targeted therapy). The recurrence rate after surgical resection is as high as 50%-80% [2], and once recurrence occurs, only a very small number of patients can be operated again; therefore, recurrence and retreatment after surgery has become a hot spot and a difficult area in the treatment of liver cancer. According to Cho et al [3], the recurrence rates of small hepatocellular carcinoma are similar between surgical resection and ablation therapy, but ablation therapy has the advantages of less trauma, lower surgical mortality, fewer complications, and the ability to re-treat with ablation after recurrence, so local ablation therapy has become one of the main means of treatment for non-surgical resection of hepatocellular carcinoma. From April 2008 to April 2010, we applied microwave ablation under ultrasound guidance to treat 39 patients with recurrence of hepatocellular carcinoma after surgery, and we report them as follows. 1.1 Clinical data Thirty-nine patients with recurrent liver cancer after surgery, 25 males and 14 females, aged 42-74 years, average age 53 years, all 39 cases were single lesions, recurrent lesions were 2.5-7.2 cm in diameter (Q3.5 cm in 20 cases, 3.5-5.0 cm in 10 cases, >5.0 cm in 9 cases); liver function was Child A in 24 cases and B in 15 cases. 1.2 Instruments and equipment Color ultrasound machine: Philips CX50 (device number 453561373772), probe C5-1. microwave ablation therapy instrument: MTC-3C microwave ablation therapy instrument (Nanjing Qinghai Microwave Electronics Research Institute, registration standard: YZB/Guo 1408-2003. product registration certificate number: State Food and Drug Administration Machinery (permitted) word 2007 No. 3251059 ), microwave transmission frequency of 2450 ± 50MHz, output power: continuous wave 0 ~ 100W output adjustable step by step. Microwave antenna effective length 100–180mm, outer diameter 14G–20G, the tip is long conical, using water circulation cooling system to reduce the antenna surface temperature. 1.3 Methods 1.3.1 Anesthesia Local anesthesia was used. The local anesthesia was administered by fasting for 12 h before surgery, establishing intravenous access to the lower extremities, administering morphine 10 mg subcutaneously and diazepam 10 mg intramuscularly half an hour before surgery to prevent pain and sedation; flurbiprofen 50 mg was administered 15 min before surgery and then 50 mg 8 h after surgery. 2% lidocaine + cocaine bupivacaine (conventional preparation 5% lidocaine 10 ml + bupivacaine 37.5 mg) was used. Add saline diluted to 40 ml) local layer by layer anesthesia to the tumor site. 1.3.2 Surgical procedure One day before surgery, combined with CT or MR images of tumor recurrence, the site of recurrent tumor, size, tumor blood supply, the presence of cancer emboli in the portal vein system, and the distance to the bile ducts, gallbladder and large blood vessels were checked by color ultrasound. Determine the appropriate surgical position (supine or lateral), puncture access and body surface puncture site. The skin is routinely disinfected at the puncture site, a surgical towel is placed, and the ultrasound probe and cable are “isolated” with a laparoscopic sleeve. Local anesthesia was applied to the puncture site as described above, and the skin was broken with a sharp knife blade. The microwave ablation antenna is inserted layer by layer under ultrasound guidance according to the pre-determined puncture channel with appropriate adjustment of the angle to stop at the bottom of the tumor (single ablation antenna for tumor Q3.5 cm, two ablation antennas for 3.5-5.0 cm; three ablation antennas for >5.0 cm). Connect the cold circulation system, connect the ablation cable, and turn on the power of microwave ablation machine for treatment. The microwave ablation output power is generally 60-80W, and the ablation time is set to 4-10 min according to the size of the tumor, and the echogenicity of the tumor is gradually enhanced and expanded under the ultrasound until it is completely covered by the strong echogenicity (the strong echogenicity is caused by the water vapor generated in the tumor tissue during heating). At the end of the treatment, the needle was slowly withdrawn and the needle tract was cauterized to prevent bleeding and needle tract implantation metastasis. The patient’s vital signs and pain were monitored intraoperatively. Postoperative salt bag lap band with pressure bandage, fasting and water fasting for 4h, bed rest for 24h, treated with hepatoprotection, hemostasis and infection prevention, and monitored vital signs for 24h. 5-7 days after surgery if obvious side effects and complications can be discharged. 1.4 Imaging examination and efficacy judgment One month after the end of treatment, intensive CT (15 cases) or MRI (24 cases) was performed to determine whether the ablation was complete [4-6], and those who were not completely ablated could continue the treatment. the criteria for complete ablation of tumor by CT examination: no enhancement in the arterial phase and venous phase of the lesion area; the criteria for complete ablation of tumor by MRI examination: complete low signal in the tumor area by enhancement scan. The criteria for complete ablation of tumor by CT: no enhancement in the arterial and venous phases of the lesion; the criteria for complete ablation by MRI: complete low signal in the tumor area on enhancement scan. 1.5 Follow-up Follow-up was conducted every 3 months after discharge, and the cause of death was registered for patients who died, and the survival rates of 1, 2 and 3 years were calculated respectively. 1.6 Statistical methods The Kaplan-Meier method was used to calculate the survival period. 2, Results 2.1 Efficacy 1 month after treatment, 35 of the 39 lesions met the criteria for complete ablation by CT or MRI, 4 lesions were not completely ablated, one-time complete ablation rate: 89.7%. 4 lesions that were not completely ablated were all >5.0 cm, including 1 lesion of 7.2 cm with irregular morphology. 4 lesions that were not completely ablated were microwave ablated again. The four lesions that were not completely ablated were re-ablated by microwave, and all achieved complete ablation after surgery. At 3 months after surgery, all lesions met the criteria for complete ablation on CT or MRI. 2 lesions recurred at 6 months on CT or MRI (1 patient with a maximum tumor meridian of 4.0 cm and 1 patient with a maximum tumor meridian of 5.2 cm), and microwave ablation was performed in these 2 patients (both achieved complete ablation after surgery). Four patients had local recurrence of the tumor (7.2 cm, 3.8 cm, 4.0 cm, and 5.0 cm) on CT or MRI 9 months after surgery, and three patients underwent microwave ablation (complete ablation after surgery). The patient with the largest lesion of 7.2 cm gave up treatment. At 12 months after surgery, three patients had local recurrences (one patient with a maximum tumor meridian of 3.8 cm, one patient with a maximum tumor meridian of 4.2 cm, and one patient with a maximum tumor meridian of 5.5 cm), one patient underwent microwave ablation again (complete ablation after surgery), and two other patients (patients with a maximum meridian of 4.2 cm and a maximum meridian of 5.5 cm) gave up treatment. The overall recurrence rate within 12 months was 23.1%. The follow-up period ranged from 8 to 36 months, and the 1-, 2-, and 3-year survival rates were 78.8%, 45.5%, and 27.3%, respectively. 2.2 Side effects and complications 2.2.1 Side effects 2.2.1.1 Pain: The procedure was performed under local anesthesia, and pain was generally experienced to varying degrees during the ablation process. In this group of 39 patients, 48 ablations were performed, and moderate pain occurred in 10 cases, among which severe pain occurred in 4 cases (all tumors were located under the liver envelope. When severe pain occurred, the operation was stopped, morphine was injected subcutaneously again, and sedative such as imipramine was injected slowly intravenously at the same time, and ablation was started about 10 minutes later); 4 cases of moderate pain occurred after the operation, and no 1 case of severe pain occurred. 2.2.1.2. Post-ablation syndrome: The main symptoms were fever (below 38.5℃), malaise, general malaise, nausea, vomiting, etc. In our group, 39 patients underwent 48 ablations and post-ablation syndrome occurred in 17 cases. There were no serious complications such as severe bleeding, biliary fistula, intestinal fistula and deterioration of liver function in 48 cases. 6 cases had transient elevation of glutamate transaminase (all below 150 IU/L, which recovered in about 1 week after treatment with hepatoprotective drugs). 1 case had oliguria, creatinine and urea nitrogen increase 12 hours after ablation, followed by acute renal insufficiency (treated with diuretics). One case of acute renal insufficiency occurred 12 hours after ablation (creatinine and urea nitrogen decreased after 7 d of treatment with diuresis, vasodilatation, correction of electrolyte and acid-base balance disorders, and entered the polyuric phase. 10 d later, urine volume returned to normal and creatinine and urea nitrogen decreased to normal). one case of purulent infection occurred at the lesion 10 d after ablation (pus culture was E. coli, and the infection was effectively controlled after intubation and effective antibiotic treatment). 3. Discussion We treated 39 postoperative recurrent hepatocellular carcinoma patients with 39 lesions using different numbers of microwave ablation antennas (single for lesion Q3.5 cm, two for 3.5-5.0 cm, and three for >5.0 cm) according to the size of the lesion. For lesions Q3.5 cm and 3.5-5.0 cm, the one-time complete ablation rate could reach 100% (30/30), suggesting that microwave ablation for liver cancer lesions Q5.0 cm could achieve the same results as surgical resection with one-time complete local inactivation. For lesions >5.0 cm, the one-time complete ablation rate was 44.4% (4/9). 4 patients in this group with lesions >5.0 cm did not achieve complete inactivation after the first ablation, and we performed the second ablation for these 4 patients, and complete ablation was achieved after the second ablation, which indicates that if liver cancer lesions >5.0 cm are treated even with three microwave ablation antennas, it is sometimes difficult to achieve complete local inactivation. This indicates that if the liver cancer lesion is >5.0cm, even if the treatment is performed with three microwave ablation antennas, it is sometimes difficult to achieve complete local inactivation at one time, and it is necessary to perform ablation in stages. The recurrence of liver cancer after local ablation is one of the most difficult problems in clinical treatment. 39 patients in this group had 9 recurrences within 12 months, with a local recurrence rate of 23.1%. 9 patients with recurrence had a maximum tumor diameter of 3.8 cm-7.2 cm, and the remaining 30 patients with Q3.7 cm had no recurrence, which indicates that local recurrence has a greater relationship with tumor size. For local recurrence, ablation can still be performed again. 6 of the 9 recurrences in this group were ablated again, and all of them achieved complete ablation. The survival rates at 1, 2, and 3 years were 78.8%, 45.5%, and 27.3%, respectively, according to the follow-up results of this group. Although the number of cases in this group is small, it still shows that microwave ablation can achieve a long survival period for recurrent liver cancer after surgery. There were no perioperative deaths in 39 patients, and no serious complications such as severe bleeding, biliary fistula, intestinal fistula, or deterioration of liver function occurred in 48 cases, which is similar to those reported by other scholars [7]. 6 cases had transient elevation of glutamate transaminase, which recovered after treatment with hepatoprotective drugs. 1 case had acute renal insufficiency 12 hours after ablation, which was treated with diuresis, vasodilation, and correction of electrolyte and acid-base balance disorders after 10 d. One case of acute renal insufficiency occurred 12 hours after ablation, but the urine volume returned to normal and creatinine and urea nitrogen decreased to normal after 10 d of treatment, including diuresis, vasodilation, correction of electrolyte and acid-base balance disorders, etc. One case of purulent infection occurred at the lesion after ablation, and the infection was effectively controlled after intubation and drainage and effective antibiotic treatment. In conclusion, microwave ablation is effective in the treatment of recurrent liver cancer, especially for the largest diameter Q3.7cm liver cancer can be completely ablated at one time, and the rate of local recurrence is low. In addition, microwave ablation has the advantages of large ablation range, short ablation time, simultaneous application of multiple microwave sources, and the possibility of re-ablation after recurrence. The complications of liver cancer after recurrence of microwave ablation treatment are relatively few and can be controlled.