China is a country with high incidence of liver cancer, and more than 50% of liver cancers occur in China. The 3-year survival rate of small liver cancer treated with low-segmentation high-dose by applying stereotactic technique in China is comparable to that of surgery, which is the leading international level. Liang Xia et al. applied radiotherapy to treat hepatocellular carcinoma ≤5 cm in diameter with a segmentation dose of 2-6 Gy (median 5 Gy) and 6-35 irradiation sessions (11±3 sessions), and the patients had a 3-year survival rate of 60% with no treatment-related deaths; Chen Longhua and Guan Jian used 48-63 Gy/6-9 sessions/12-18 days radiation to treat hepatocellular carcinoma ≤5 cm in diameter, and the 3-year survival rate reached 97%; Li Ping and Xia Tingyi used hepatic artery embolization (TACE) followed by body gamma knife radiotherapy for stage I and II hepatocellular carcinoma (3~5 Gy/5 times/2~3 weeks) with a total tumor center of 80~102 Gy, and the 3-year survival rate was as high as 100%. Our hospital has also achieved very satisfactory results with a split dose of 50 Gy/10 times/2 weeks of radiotherapy (related article is pending publication). Zhang Zhigao, Department of Gastroenterology, General Hospital of Jinan Military Region, on the selection of radiotherapy fractionation dose for hepatocellular carcinoma The occurrence of radiation liver disease is not only related to the radiotherapy dose, but also to the degree of cirrhosis, the volume of the irradiated liver and the three-dimensional conformal dose distribution. It is the author’s experience that the degree of cirrhosis is the main factor that limits the radiotherapy dose and leads to radiographic liver disease. Theoretically, hypodivision is more likely to cause damage to normal liver tissues than conventional division, but in clinical work, radiographic liver disease due to hypodivision high-dose therapy is rare for liver cancer with small tumor diameter (≤5 cm) and ideal dose distribution. Can the radical dose of radiotherapy for hepatocellular carcinoma be achieved if the segmentation and total amount (2 Gy/time, once a day, five times a week, total dose 50-62 Gy) specified by the Expert Consensus on Standardized Diagnosis and Treatment of Primary Liver Cancer are used? In clinical work, it is found that such fractionation and total amount are far from being able to cure liver cancer. Therefore, for nodal hepatocellular carcinoma with tumor ≤5 cm, Child-Pugh grade A liver function and ideal three-dimensional conformal dose distribution, low-segmentation and high-dose radiotherapy should be advocated in order to achieve radical effect. For hepatocellular carcinoma with small tumor size and the surrounding normal tissues within the permissible range, the use of multifield conformal hypofractionated high-dose radiation therapy will not only not cause serious complications, but also improve the local control rate and cure rate of the tumor by shortening the treatment course. As in case 1, the patient had a small tumor and a well-tolerated liver, so the effect of the high-dose area on the liver should be considered first. As shown by the two-dimensional cross-sectional map and dose volume histogram (DVH) (see Figures 1 and 2), the high dose area of conformal irradiation is significantly lower than that of counter-penetrating irradiation (e.g., 50% to 80% of the corresponding volume of conformal irradiation is about half of that of counter-penetrating irradiation). Therefore, conformal irradiation should be chosen as the treatment option. Further analysis showed that conformal irradiation is less damaging, can increase the single dose reasonably, and a low-segmentation approach is desirable. For larger liver tumors, we agree with Prof. Zeng that conformal low-segmentation high-dose radiotherapy is not appropriate. Because of the large size of tumor, most of the liver should be irradiated by high dose, the normal liver tissues available for compensation are small, and the dose tolerance threshold of liver is low, at this time, the impact of low dose area on liver should be considered first, and the adoption of low segmentation mode will make the low dose area larger and prone to serious radiotherapy complications. As in the case of large hepatocellular carcinoma (example 2), as seen by the DVH map (see Figure 4), the difference between the two liver exposure is small, but the two-dimensional cross-sectional map suggests that conformal irradiation exposes the left half of the liver lobe to greater than 40% of the dose (see Figure 3), which affects its compensatory function, so balancing the pros and cons against penetrating irradiation is preferable. Moreover, assuming an injury threshold of about 40%, if conformal irradiation is applied and low split treatment is used, after converting to equivalent biological dose, the whole blue curve will be shifted to the upper right and the volume beyond the threshold dose will become larger rapidly. We can view the dose splitting approach according to the 4R theory of cell proliferation and cell damage repair. For tumor tissues, their cells will proliferate after irradiation, and increasing the splitting dose helps to inhibit the proliferation of tumor cells; while for late response normal tissues, their cells need to repair after irradiation, and increasing the splitting dose is detrimental to the repair of these tissues. It can be seen that segmentation dose is a double-edged sword, and there are advantages and disadvantages of using both conventional segmentation and low segmentation. Therefore, whether it is liver cancer or other tumors, we should consider the specific situation and adopt the appropriate fielding method and segmentation dose without serious complications, so as to obtain good curative effect. Summary Comprehensive tumor treatment is the development direction of today’s tumor treatment, which emphasizes the use of multidisciplinary and multi-methods so as to give different tumor patients a targeted and comprehensive treatment plan. In choosing radiation therapy, we should also integrate various factors, compare and analyze from multiple perspectives, and find out the optimal plan. No matter irradiation method or segmentation method, there is no one treatment method that can be applied to all cases. Therefore, individualized treatment is the only way to meet the development requirements of modern tumor radiotherapy. Professor Zeng Zhaochong shared his rich clinical experience with his colleagues, and Professor Li Gong also put forward different views on the issues related to the fractionation dose of radiation therapy for liver cancer with his own clinical experience and cases. In this issue of Oncology Weekly, we publish Prof. Zeng Zhaochong’s reply, and we also expect more readers to participate in the discussion.
Excerpted from Medical Tribune