Currently, chemotherapy, targeted therapy, immunotherapy, and radiotherapy are the core treatment modalities for malignant tumors, with technologies advancing rapidly. Radiotherapy can induce massive tumor cell death in a short period and expose abundant tumor-specific antigens, turning the irradiated tumor into an endogenous tumor vaccine and even causing regression or disappearance of non-irradiated tumors (the abscopal effect) . Preclinical studies have shown that stereotactic body radiotherapy (SBRT) combined with PD-1/PD-L1 inhibitors can activate systemic immunity, sensitize tumor-specific T cells to enter the bloodstream, and enable their homing to distant tumors, thereby inhibiting the growth of non-irradiated tumors . However, conclusions from rigorous randomized controlled trials have limitations when applied to the complex and heterogeneous patient populations in real-world settings. Real-world research is increasingly valued globally to complement traditional clinical trial evidence. This project prospectively collects data from patients receiving immunotherapy combined with radiotherapy in real-world clinical practice, which is of great value for evaluating long-term efficacy, safety, and impact on quality of life, and can provide high-level evidence for optimizing clinical practice and informing healthcare decisions.

Inclusion Criteria:

1. Age ≥ 18 years;
2. Histologically or cytologically confirmed malignant tumor;
3. Planned to receive immunotherapy combined with radiotherapy as the basis of treatment;
4. At least one measurable lesion according to the Response Evaluation Criteria in Solid Tumors (RECIST 1.1);
5. Adequate organ function (reference may be made to laboratory test indicators, such as routine blood tests, liver and kidney function);
6. Voluntarily participate in this study, sign the informed consent form, and agree to comply with follow-up.

Exclusion Criteria:

1. Patients with severe cognitive impairment, mental illness, or other conditions that, in the judgment of the investigator, preclude them from cooperating with participation in this study;
2. Active, uncontrolled serious infection, or known human immunodeficiency virus (HIV) infection;
3. Pregnant or breastfeeding women;
4. Any unstable systemic disease (including but not limited to severe cardiac, hepatic, or renal insufficiency).

Patients aged ≥18 years with histologically or cytologically confirmed malignant tumors who are planned to receive treatment based on immune checkpoint inhibitors combined with radiotherapy.