ContextSCLC has had few drugs for treatment and a high malignancy rate. About two-thirds of SCLC patients have distant metastasis by the time they receive a diagnosis, and once it occurs, patient's survival time is short. Immunotherapy treatments can block immunosuppression and increase the body's antitumor ability. PD-1 is the main immune checkpoint of tumors' immune response, and PD-L1 is one of the ligands of PD-1.ObjectiveThe study intended to analyze the therapeutic effects of inhibitors of programmed death-1 (PD-1)/ programmed cell death 1 ligand 1 (PD-L1) combined with chemotherapy for patients with advanced small cell lung cancer (SCLC), evaluate the safety of that treatment, and compare it with chemotherapy alone.DesignThe research team performed a retrospective randomized controlled study.SettingThe study took place at Cangzhou Central Hospital.ParticipantsParticipants were 72 patients with advanced SCLC who received treatment at the hospital between December 2021 and December 2022.InterventionThe research team divided participants into two groups, each with 36 participants, using the random number method: (1) the control group, which received platinum-etoposide chemotherapy, and (2) the intervention group, which received a PD-1/PD-L1 inhibitor combined with the same chemotherapy that the control group received.Outcome MeasuresThe research team examined: (1) short-term efficacy; (2) long-term efficacy; (3) tumor-marker levels-neuron-specific enolase (NSE), progastrin releasing peptide (ProGRP), cytokeratin-19-fragment (CYFRA21-1), and squamous cell carcinoma antigen (SCCA); (4) T lymphocyte-subset levels-cluster of differentiation 3+ (CD3+), CD4+, and CD8+; (5) adverse reactions, and (6) Karnofsky performance status (KPS) scores.ResultsCompared with the control group, the intervention group's: (1) overall response rate (ORR), with P = .002, and disease control rate (DCR), with P = .041, were significantly higher; (2) median survival time was significantly longer (P = .035); (3) levels of NSE, ProGRP, CYFRA21-1, and SCCA were significantly lower (all P < .001); (4) levels of CD3+ (P = .043) and CD4+ (P < .001) levels were significantly higher; and (5) Karnofsky performance status (KPS) scores were significantly higher than those of the control group (P = .018). No difference existed in the number of adverse reactions between the groups (P > .05).ConclusionsThe PD-1/PD-L1 inhibitor combined with chemotherapy can benefit advanced SCLC patients, controlling patients' conditions and improving their quality of life, with good safety.