Liver cancer (mainly referring to hepatocellular carcinoma) has a high incidence rate and great danger in China. At the present stage in China, due to the lack of awareness of high-risk groups and early diagnosis of liver cancer, screening is far from popular, the early detection rate of liver cancer still needs to be improved, and large hepatocellular carcinoma (maximum diameter greater than 5 cm) is still the most dominant type of liver cancer.
Large hepatocellular carcinoma has distinct clinical characteristics: it is often accompanied by peripheral satellite foci, portal vein branch embolism or even intra- and extra-hepatic metastases; the scope of the cancer is larger than the scope of the lesions shown by CT or MRI; it is often accompanied by different degrees of viral hepatitis and cirrhotic background with poor liver function reserve; due to years of liver disease treatment, patients’ families are often not in a generous financial position.
The treatment decision of large liver cancer is not as simple and easy as early liver cancer. Specifically, liver resection for large hepatocellular carcinoma often requires removal of a large area of normal liver tissue, which has a greater impact on liver function and higher complication rate, and often cannot completely remove the lesion. Although transarterial interventional chemoembolization has a certain effect on controlling the volume of liver cancer, it can promote the metastasis of peripheral cells, so it is difficult to obtain satisfactory therapeutic effect by simple application. Due to the uncertainty of the above treatment tools, different physicians with different professional perspectives may make different treatment decisions for the same large liver cancer patient, which often makes patients torn.
Radiofrequency ablation is a new technology developed in the last decade or so for the treatment of liver cancer. Its principle is to destroy cancer tissues by causing ions in cancer tissues to oscillate at high speed through radiofrequency current, generating a temperature of about 105℃. This technique is a masterpiece of local treatment for liver cancer, which has definite efficacy on liver cancer and has the advantages of simple operation, minimal trauma, low requirement on liver function and low cost, which is easily accepted by patients. Radiofrequency ablation has now become one of the curative means for early liver cancer, and can be the first choice treatment for early liver cancer, playing an increasingly important role in the comprehensive treatment of liver cancer.
In the early stage of radiofrequency ablation, due to the reasons of equipment, technology and experience, the size of lesion for radiofrequency ablation treatment of liver cancer was limited to less than 5 cm in diameter. This largely standardized the clinical application of RF ablation and laid the foundation for the healthy development of RF ablation for liver cancer. In the past five years, the application of radiofrequency ablation in comprehensive treatment of liver cancer has become more and more extensive, experience has been gradually accumulated, radiofrequency ablation equipment has been significantly improved, and more importantly, the level of understanding of liver cancer has become more in-depth and systematic, all of which have laid the foundation for the adoption of radiofrequency ablation treatment for large liver cancer, so that some carefully selected large liver cancers have obtained satisfactory curative effects through comprehensive treatment based on radiofrequency ablation. The important measures to ensure the efficacy of radiofrequency ablation for large hepatocellular carcinoma are divided as follows.
I. More comprehensive scientific understanding of liver cancer
Looking at hepatocellular carcinoma from the biological characteristics is a leap forward in the understanding of hepatocellular carcinoma in recent years. The traditional view is that in the process of occurrence and development of hepatocellular carcinoma, the cells with strong invasive and high metastatic potential change from less to more, and the larger the tumor, the higher the malignancy, and the higher the incidence of infiltrative metastasis. Thus, it is believed that hepatocellular carcinoma larger than 5 cm in diameter is often accompanied by peri-cancerous infiltration and/or metastasis from other sites and is not suitable for local treatment such as radiofrequency ablation. Modern studies have shown that the biological characteristics of hepatocellular carcinoma are defined at the primary tumor stage and do not change with its development. On the contrary, for those with strong invasive metastatic ability, micro-venous metastasis is not easy to occur during the growth process, and even if the cancer foci are large, the lesions are still relatively limited and suitable for local treatment, and complete ablation and satisfactory curative effect can be easily obtained.
The above-mentioned improvement in understanding has, to some extent, questioned the traditional view of applying the size of tumor to regulate the indications for radiofrequency ablation treatment, and laid the theoretical foundation that radiofrequency ablation can be applied to isolated large hepatocellular carcinoma to obtain satisfactory results.
II. Richer experience of radiofrequency ablation for large hepatocellular carcinoma
1. Combined application of transhepatic artery interventional chemoembolization
The main pathophysiological feature of hepatocellular carcinoma is rich arterial blood supply, and these rich arterial vessels can take away the heat from the ablation foci, which affects the efficiency and efficacy of radiofrequency ablation. This is especially true for large hepatocellular carcinoma. To address this problem, applying transarterial interventional chemoembolization prior to RF ablation can effectively reduce the arterial blood supply within hepatocellular carcinoma and enhance the efficiency and efficacy of RF ablation. In addition, pre-emptive interventional embolization can also fill the liver cancer tissue with iodine, which is beneficial to the accuracy of CT-guided needle placement.
2. Radiofrequency ablation under laparoscopy
Large hepatocellular carcinoma is often closely related to important structures such as diaphragm, gallbladder, colon, stomach and duodenum, which makes it difficult to adopt percutaneous puncture route and prone to complications such as damage to important structures. For this case, laparoscopic radiofrequency ablation can provide a clearer, more intuitive and comprehensive view, and the puncture angle is more free and applicable, and the safety can be significantly improved.
3. Repeat radiofrequency ablation
For large hepatocellular carcinoma, it is difficult to obtain complete ablation by one time radiofrequency ablation, so multiple radiofrequency ablation is often needed. Modern research shows that repeated radiofrequency ablation can enhance the anti-tumor immune function of the body. During the first radiofrequency ablation, tumor cells and some normal hepatocytes are degenerated and necrotic, and a large amount of self-antigenic components are introduced into blood, which can activate tumor-specific T lymphocyte response. Repeated RF ablation within a short period of time, a large number of auto-antigen components enter the blood again, and T lymphocytes proliferate in large numbers, so that the anti-tumor immune function of the body is obviously enhanced.
4. Painless assurance and respiratory support
The duration of radiofrequency ablation treatment for large hepatocellular carcinoma can be up to 2 hours or more. General anesthesia and respiratory support can eliminate patients’ tension and pain, give patients a relaxation, give physicians a calmness and give a guarantee of therapeutic effect.
Third, radio frequency ablation equipment is more excellent
The maximum diameter of single point ablation foci of traditional RF ablation system is 5 cm, and it takes at least 15 minutes. To treat cancer foci with a diameter of 7 cm, it takes at least 6 points of superimposed ablation, which takes nearly 2 hours to achieve complete ablation. Now, the radiofrequency ablation system with single point ablation range of 7.0 cm and single point ablation time of only 12 minutes has been applied in clinical practice, which has greatly improved the ablation efficiency of large liver cancer.
IV. Radiofrequency ablation treatment for large liver cancer is more standardized
Preliminary experience shows that minimally invasive treatment based on radiofrequency ablation can be considered for large hepatocellular carcinoma with the following characteristics.
1.Single or isolated nodular carcinoma foci with intact envelope or with pseudo-envelope.
2, tumor is unresectable or the patient refuses surgery.
3, preoperative imaging shows no satellite foci or extrahepatic metastases.
4, no obvious signs of large vessel or biliary tract invasion.
5, good liver function reserve.
6, no serious heart, brain, liver, kidney or other organ dysfunction.
Radiofrequency ablation should not be applied if one of the following characteristics is present.
1, Uncorrectable coagulation dysfunction.
2, recent bleeding from ruptured esophageal (fundic) varices.
3, poor liver function reserve.
4, major organ insufficiency.
5, active infection, especially inflammation of the biliary system, etc.
6, impaired consciousness or cachexia.
V. Preliminary results are promising
Takaki et al. summarized the clinical data of 20 cases of large hepatocellular carcinoma treated with combined radiofrequency ablation and interventional embolization, and the results showed that the survival rates at 1, 3 and 5 years were 100%, 62% and 28%, respectively. The results showed that the 1-year and 2-year survival rates were 68% and 56%, respectively, for large hepatocellular carcinoma with a follow-up of 3 to 36 months and a mean of 14 months. It is suggested that for large hepatocellular carcinoma with a diameter of 5.0 cm to 9.0 cm, complete ablation can be safely obtained by applying radiofrequency ablation. In the past 12 years, the authors have conducted a more systematic exploration of the value of radiofrequency ablation in the comprehensive treatment of hepatocellular carcinoma and proposed a series of measures to further enhance the efficacy of radiofrequency ablation for large hepatocellular carcinoma, and achieved promising preliminary results, some of which have been published in domestic and international journals.
In conclusion, the efficacy of large hepatocellular carcinoma needs to be further improved and the treatment needs to be further standardized. Although a considerable proportion of large liver cancers cannot be cured by surgical resection, they are not so advanced that active treatment is unnecessary. For carefully selected large hepatocellular carcinoma, the minimally invasive treatment based on radiofrequency ablation can achieve satisfactory results.