Safety and Efficacy of Radiotherapy Combined with Immunotherapy for Advanced Malignant Tumors.

Inclusion Criteria:

1. advanced malignant solid tumors with multiple metastases or relapses, with pathological diagnosis or medical record;
2. disease progression or recurrence after standard treatment, or unsuitable/intolerable for standard treatment, or rejection of standard treatment due to personal willingness;
3. patients with disease progression or drug resistance after previous immunotherapy are allowed to be included; a history of radiotherapy in the LDRT area or other sites is allowed to be included, provided that there are no residual toxic effects;
4. at least ≥1 lesion suitable for SBRT, and ≥1 lesion suitable for LDRT, and the above lesions must be measured;
5. no contraindications to radiotherapy;
6. Eastern Cooperative Oncology Group (ECOG) score: 0-2 points, and life expectancy \>3 months;
7. important organ function is acceptable, defined as: white blood cells ≥3.0×10\^9/L, platelets ≥75×10\^9/L, hemoglobin ≥90g/L, glutamic pyruvic transaminase and glutamic oxalacetic transaminase ≤2.5 times the upper limit of normal value, serum creatinine \< 178μmol/L;
8. voluntary participation and sign the informed consent.

Exclusion Criteria:

1. no suitable lesions for radiotherapy, or the limit of important organs at risk could not be met;
2. permanent discontinuation of PD-1/L1 inhibitors due to ≥ grade 3 immune-related toxic reactions;
3. serious cardiovascular or cerebrovascular diseases, severe liver or kidney dysfunction, serious and uncontrolled systemic infections or other contraindications, or any contraindications to radiotherapy, and some comorbidities should be re-evaluated after symptomatic treatment;
4. any active immune system disease or related history;
5. systemic immunosuppressive drugs are expected to be used during the study;
6. a history of severe uncontrollable central nervous system diseases or mental disorders, which may hinder the signing of informed consent or treatment compliance;
7. other important medical or physiological conditions (such as pregnancy or breastfeeding status);
8. patients who are known to be allergic to the drugs used in this study;
9. patients refuse or are unable to sign the informed consent.