With the development and improvement of various new technologies, diseases previously thought incurable are now well or even cured, and the development of liver cancer treatment technology fully illustrates this point. In addition to traditional surgical resection and hepatic artery interventional embolization treatment, new methods invented in recent years include minimally invasive treatment methods represented by microwave, radiofrequency and argon helium knife, drug-targeted therapy represented by sorafenib, as well as biological immunotherapy and liver transplantation.
Among them, the most effective, safest, least side effects, most economical, simplest operation and shortest operation time is the cold circulation microwave ablation technology, while ultrasound-guided percutaneous microwave ablation has great advantages in the treatment of liver or other organs due to its advantages of real-time guidance and monitoring, precise positioning, complete ablation, no radiation, immediate intraoperative examination and can be repeated several times in a short period of time, thus In recent years, it has been widely used in the fields of liver cancer, kidney cancer, lung cancer, prostate cancer, thyroid cancer, gynecological tumors, etc., and even intermediate and late stage tumors can be treated with satisfactory results. The following are some excerpts from the summary.
Indications and Contraindications
Ultrasound-guided percutaneous microwave therapy has a wide range of indications. It can be applied to patients with primary liver cancer without serious liver and kidney dysfunction or serious coagulation dysfunction, patients with recurrence of liver cancer after hepatectomy and patients with liver metastases. Based on the technical performance of the treatment system, the indications and contraindications can be determined according to the differences in clinical patient’s whole body, tumor shape, size, invasiveness, blood flow status, tumor location and adjacent conditions, so that patients with different conditions and even different stages of liver cancer can be treated as actively and effectively as possible.
I. Indications
Based on the condition and the purpose of treatment, indications can be divided into three categories: radical treatment, subradical treatment and palliative treatment.
1.Curative treatment
Microwave therapy is required to achieve complete tumor necrosis, i.e. in situ conformal coagulation and inactivation.
(1) For single tumor, the maximum diameter of tumor is ≤5cm.
(2) Multiple tumors, the number of tumors ≤ 3, the maximum diameter of tumors ≤ 3cm.
(3) No vascular, bile duct cancer embolus or extrahepatic metastases.
(4) The distance of the tumor from the common hepatic duct, right and left hepatic duct or gastrointestinal duct in the hilar region is at least 5 mm.
(5) Liver function Child grade A or B, no ascites or small amount of ascites.
2.Sub-radical treatment
The patient’s condition is worse than radical treatment, and generally requires multiple electrodes and combined thermal fields for multiple treatment points, or combined with other treatment methods to strive to achieve complete necrosis of the tumor.
(1) Single tumor, the largest diameter of tumor > 4cm, but generally ≤ 8cm, can first hepatic artery cannulation chemoembolization, blocking the tumor blood supply vessels, and then microwave therapy. This helps to improve the thermal efficiency and increase the coagulation range.
(2) Multiple tumors, the number of tumors ≤ 5, the maximum diameter of the tumor ≤ 5 cm, such as blood supply is not rich, can be directly microwave therapy; such as blood supply is rich, can first hepatic artery cannulation chemoembolization, and then microwave therapy.
(3) There is portal vein cancer thrombus, but the cancer thrombus is confined below the tertiary branch of portal vein, and the blood flow of this section can be directly blocked by microwave.
(4) Liver metastatic cancer, no matter single or multiple tumors, must be combined with systemic chemotherapy or endocrine therapy (for endocrine-dependent tumors such as prostate cancer or breast cancer), etc., and attention should always be paid to the condition of the primary lesion.
(5) When the tumor is close to the bile ducts and gastrointestinal ducts of the hepatoportal area, in order to prevent the damage of the above-mentioned structures caused by the high temperature area of microwave, or when the tumor is close to the larger blood vessels, forming a local “cold area” and leaving residual cancer, the tumor can be treated with local injection of ethanol before microwave treatment.
3.Palliative treatment
It is mainly for those patients whose tumors are too large and cannot be treated surgically, and other methods such as hepatic artery chemoembolization have no obvious effect. The purpose of treatment is to reduce the tumor load in order to slow down the disease, reduce pain and prolong life. These patients often have heavy disease, large tumors and a large number of tumors. The first consideration in microwave therapy is safety and discretionary treatment for tumor reduction. The volume of coagulation should not be too large each time, and the number of tumors should not be too many, focusing on the coagulation of the peripheral area of the tumor.
It should be noted that due to the complexity of hepatocellular carcinoma and the difference of individual response to treatment, there is no absolute distinction between the above three treatment modalities. Some patients who were in the radical treatment group before treatment may be converted to subradical treatment if new metastatic lesions are found during treatment. With the development of various technical means and methods, such as through the improvement of microwave coagulation treatment system or through three-dimensional ultrasound-guided multi-electrode combination technology, the ability of microwave coagulation conformal control is further enhanced, today’s subradical treatment patients may also become radical treatment tomorrow.
II. Contraindications
1, there is a serious coagulation dysfunction, platelets < 40 * 109 / L, prothrombin time > 30s, prothrombin activity < 40%, after transfusion, the administration of hemostatic drugs and other treatment is still not improved.
2, a large amount of ascites, after liver preservation, diuretic and other treatments still have more ascites before the liver.
3.hepatic encephalopathy is more serious and the person is in a trance.
4.Tumor volume is too large such as more than 2/3 of the liver volume, or diffuse liver cancer.
5.There are acute or active infectious lesions in any part of the body, which can be treated only after the infection is controlled.
6.Tumor is less than 0.5cm from the hilar part of liver, common bile duct, left and right hepatic ducts and gallbladder should be used with caution.
Pre-operative preparation
1. Before treatment, patients should have routine blood check, complete set of liver function, prothrombin time and activity, electrocardiogram and chest X-ray for patients over 50 years old, and blood glucose test for diabetic patients, and it is advisable to regulate these indicators to a better state before treatment.
2. Patients should be fasted from food and water on the day of treatment, and intravenous access should be established before treatment, which is generally carried out under local anesthesia.
IV. Treatment method
The patient’s position is based on the principle that the tumor can be clearly shown on the puncture guide line during ultrasonography. The location of the liver tumor and the distribution of tumor blood vessels are shown by ultrasonography, and the route of needle entry is confirmed.
The operation area was routinely disinfected and toweled, local anesthesia, 1% lidocaine local anesthesia, and skin incision by sharp knife. Ultrasound guidance is used to feed the electrode into the punctured predetermined liver tumor site, and the combination of power and time is set according to the size of the tumor, and the action time usually takes 3-10min.
V. Imaging evaluation of clinical efficacy
The efficacy of microwave therapy for hepatocellular carcinoma is generally evaluated by comprehensive indicators, including temperature monitoring during treatment, post-treatment impactological examination, histopathological examination of lesions, clinical laboratory examination and improvement of patients’ symptoms and signs. Among them, puncture biopsy is the gold standard of evaluation, but because it is invasive and difficult to repeat, impactological evaluation is usually considered as the most important evaluation method.
1.Ultrasound evaluation: ultrasound and ultrasonography examination of hepatocellular carcinoma has the features of simplicity, speed and real time, which can determine the distribution of tumor vessels and the location of trophoblastic vessels, their diameter and blood flow rate. The gray-scale ultrasound of completely coagulated necrotic foci shows strong echogenicity centered on the needle tract, accompanied by a wider hypoechoic band in the periphery. If there is localized hypoechogenicity or arterial blood flow signal, the tumor is considered to be residual or recurrent. Ultrasonography can increase the sensitivity of the blood flow signal. Biopsy of the tumor area without arterial blood flow signal after treatment will show complete necrosis, while biopsy of the tumor with blood flow signal will show incomplete necrosis. The advantage of ultrasonography is that the location of the lesion and the puncture needle can be observed in real time, which facilitates the knowledge of the ablation treatment process. What’s more, ultrasonography can be combined with intraoperative ultrasound technique, which can reduce the rate of incomplete ablation of tumor from 16.1% to 5.9% and greatly reduce the chance of re-treatment.
2.CT evaluation: When enhanced scanning, completely necrotic hepatocellular carcinoma lesions show a diameter of the area without contrast enhancement equal to or larger than the size of the lesion to be treated. If irregular thicker reinforced areas appear locally or peripherally in the arterial phase of contrast lesions, while low or no reinforcement in the portal and parenchymal phases, this indicates the presence of residual tumors that have not been completely ablated or local recurrence. However, for the recurrence of metastatic hepatocellular carcinoma, the changes in the arterial phase of the enhanced CT scan were very minimal, yet there was relatively strong contrast enhancement in the portal phase. Within one month after ablation, the thin thickness uniform circumferential enhancement band around the lesion is generally reactive congestion and inflammatory reaction after ablation, and this area will gradually diminish and disappear with the increase of treatment time.
3. MRI evaluation: Because of the coagulation necrosis due to tissue dehydration after thermal ablation, most of the complete necrosis shows a uniform and consistent low signal on the T2-weighted image of spin echo sequence (spinecho,SE) MR, however, there are still 14% of complete necrosis with significant high signal, which may be mainly due to hemorrhage or liquefied necrosis.
VI. Complications
The most common complications are short-term pain in the liver area and hypothermia (39°C) lasting less than 3 weeks, most of which can resolve on their own without special treatment. Some scholars refer to the most frequent symptoms of hypothermia and malaise with chills, pain and nausea as post-ablation syndrome. Serious complications are rare and include: intra-abdominal bleeding requiring treatment, needle tract implantation metastasis, liver abscess, gastrointestinal perforation, and hemothorax. Fatal cases are rarely caused, such as postoperative multi-organ failure, septic shock, tumor rupture, severe biliary tract injury and liver failure due to preoperative contraindications.