Radiation Therapy

The liver is one of the most common organs for tumor metastasis. Due to its vascular anatomy (dual blood supply), malignant tumor cells can easily disseminate to the liver via the portal vein or hepatic artery. Epidemiological data show that up to 50% of colorectal cancer patients, 20–30% of breast cancer patients, and 30–40% of lung cancer patients will develop liver metastases during the course of their disease (Tsilimigras et al., 2021).

Hepatocellular carcinoma (HCC) accounts for 70–90% of primary liver cancers worldwide, with more than 900,000 new cases diagnosed annually. It is the third leading cause of cancer-related death globally (Ruiz-Margáin et al., 2021). Most patients also present with cirrhosis or chronic hepatitis, complicating treatment strategies. Even with surgery or standard therapies, the five-year survival rate remains low. Patients often experience malnutrition, reduced physical capacity, and psychological distress.

Lung cancer remains the leading cause of cancer-related mortality worldwide. Standard treatment modalities include surgery, radiotherapy, chemotherapy, immunotherapy, and targeted therapy. However, many patients are not suitable candidates for surgery due to age, comorbidities, or tumor location. In such cases, stereotactic body radiotherapy (SBRT) has emerged as a key option, delivering high-dose, precise radiation to the tumor in 1–5 sessions, achieving up to a 90% local control rate ([Beverly Hills Cancer Center, 2024]; [MSKCC, 2025]).

The abscopal effect refers to the phenomenon where local radiotherapy (RT) not only causes shrinkage of tumors at the irradiated site but also leads to regression of distant, non-irradiated tumors. The term was first introduced by radiobiologist Mole in 1953, derived from the Latin ab (away from) and scopus (target) ([Mole, 1953]).

Bladder cancer ranks as the 10th most common cancer worldwide. Treatment varies depending on disease stage: non–muscle-invasive bladder cancer (NMIBC) is typically managed with BCG intravesical immunotherapy, whereas muscle-invasive bladder cancer (MIBC) often requires radical cystectomy (RC) with lymph node dissection([turn0search9]; [turn0search10]).