Ultrasound-guided percutaneous microwave therapy for hepatocellular carcinoma has a wide range of indications. It can be applied to patients with primary liver cancer without serious liver or kidney dysfunction or without serious coagulation dysfunction, patients with recurrence after hepatectomy and patients with liver metastatic tumors. However, because the systemic and focal conditions of clinical hepatocellular carcinoma patients vary greatly, especially the differences in tumor shape, size, invasiveness, blood flow status, as well as the location and adjacent conditions of the tumor, the difficulty and effect of interventional treatment can be significantly affected.
Therefore, based on the technical performance of the treatment system, it is necessary to determine the indications and contraindications according to the clinical conditions of patients’ whole body and lesions, 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 disease, indications can be divided into three categories according to the purpose of treatment: radical treatment, subradical treatment and palliative treatment.
(I) Radical treatment
Microwave therapy is required to achieve complete necrosis of tumor, i.e. in situ conformal coagulation and inactivation.
1.Single tumor, maximum tumor diameter ≤ 4cm.
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.Child grade A or B liver function, no ascites or small amount of ascites.
(ii) Sub-radical treatment
The patient’s condition is worse than radical treatment, and generally requires multiple electrodes and combined thermal fields for multiple treatments, or combined with other treatments to achieve complete necrosis of the tumor.
For single tumor, the maximum diameter of the tumor is >4cm, but generally ≤8cm, the hepatic artery can be cannulated for chemoembolization to block the blood supplying vessels of the tumor, and then microwave therapy can be performed. This can help 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, if the blood supply is not rich, can be directly microwave therapy; if the blood supply is rich, can first hepatic artery cannulation chemoembolization, and then microwave therapy.
3. If 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, the cancer thrombus can be coagulated first, and then the lesion can be coagulated.
4.For liver metastatic cancer, no matter single or multiple tumors, it 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.
If the tumor is close to the bile ducts and gastrointestinal ducts in the hepatoportal area, in order to prevent the damage of the above mentioned structures caused by the high temperature area of microwave, or if the tumor is close to large blood vessels, forming a local “cold area” and leaving residual cancer, the tumor can be treated with local injection of ethanol first, and then 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, there is still more ascites in front of the liver after treatment of liver preservation and diuretic.
3. Hepatic encephalopathy is heavy, 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.
Preoperative preparation
1. Before treatment, patients should have routine blood tests, 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. On the day of treatment, patients should fast from food and water. Before treatment, intravenous access should be established, usually under intravenous anesthesia, which requires close cooperation with anesthesiologists. Some small tumors with suitable sites can also be treated 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 ultrasound examination, and the patient can be placed in a lying position or right anterior oblique position with appropriate padding on the treatment side. 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 generally takes 5-10 min.
V. Impact 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: On enhancement scan, 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 venous 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 (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 less common and include: intra-abdominal hemorrhage requiring treatment, needle tract implantation metastasis, liver abscess, gastrointestinal perforation, and hemothorax. Possible causes of death include: multiple organ failure, septic shock, tumor rupture, severe biliary tract injury, and liver failure.