3.3.3 Radiotherapy for Liver Cancer

3.3.3 Radiotherapy for Liver Cancer

Currently, the main effective radiotherapy methods for liver cancer include three-dimensional conformal radiotherapy (3D-CRT), radioactive particle implantation, and boron neutron capture therapy. Although the liver is a radiation-sensitive organ, liver cancer cells are relatively insensitive to radiotherapy, so conventional radiotherapy cannot simultaneously balance tumor control probability (TCP) and normal tissue complication probability (NTCP). In contrast, the above three radiotherapy methods can better balance TCP and NTCP, safely increase the radiation dose to the target area, and minimize the radiation dose to surrounding normal tissues.

3D-CRT utilizes computer technology and tumor imaging to display the relationship between radiation dose and the target area as well as normal liver tissue, ensuring that the high-dose distribution in three dimensions matches the shape of the target area, while minimizing radiation exposure to surrounding normal tissues. It is currently the mainstream technique in radiotherapy. Stereotactic radiotherapy (SRT), a special type of 3D-CRT, uses small-field beam bundles to deliver multiple high-dose fractions to the target area. Studies have shown that SRT is particularly suitable for liver cancers and liver metastases with complex anatomical structures and multiple targets (<4), as well as for liver cancers where surgery is contraindicated due to impaired function of vital organs or difficult access to specific locations, especially in patients with cirrhosis and poor liver function who are not suitable for interventional treatment[55,56].

Radioactive particle implantation belongs to brachytherapy and, compared with three-dimensional conformal radiotherapy, has the advantages of fewer side effects and independence from respiratory motion. Permanent low-radioactivity particle implantation technology, especially ¹²⁵I implantation in liver cancer treatment, is receiving increasing attention. Nag et al.[57] have shown that ¹²⁵I particles feature low dose rates and relatively long half-lives (59.43 days), enabling them not only to directly kill tumor cells but also to inhibit tumor growth by suppressing cell proliferation and angiogenesis, thereby achieving the goal of treating liver cancer.