Tislelizumab Combined With Chemotherapy and Thoracic Radiotherapy in ES-SCLC

Inclusion Criteria: * Patients aged between 18 to 80 years old (inclusive of 18th and 80th birthdays), male or female, at the time of signing the informed consent form; * Confirmed small cell lung cancer of extensive stage by histology or cytology; * At least one measurable lesion by imaging studies (according to RECIST 1.1) with a long diameter of ≥10 mm as examined by spiral CT or MRI; * Within 3 days prior to treatment, an ECOG score of 0 to 1; * No prior antitumor treatment for extensive stage disease (if the patient has previously received chemotherapy and/or radiotherapy in the limited stage of SCLC, the treatment intent must have been curative, and there must be at least a 6-month treatment-free interval between the end of chemotherapy, radiotherapy, or chemoradiotherapy and the diagnosis of extensive stage SCLC); * Expected life span of ≥3 months; * Good function of vital organs; * The subject voluntarily joins this study, signs the informed consent form, has good compliance, and cooperates with follow-up. Exclusion Criteria: * Concurrent severe respiratory diseases: such as pulmonary fibrosis; * Presence of psychiatric disorders, hematologic diseases, autoimmune diseases, and severe primary diseases of the heart, brain, liver, or kidneys; * Uncontrolled active infections; * Known or suspected allergies to the study medication and its excipients; * Female patients who are pregnant or breastfeeding, or women of childbearing potential with a positive baseline pregnancy test; * Prior use of antitumor treatment targeting the PD-(L)1 pathway.