CTLA4 and cancer: The Web of Science, EMBASE, PubMed, Cochrane Library and CNKI databases were searched from their inception to July 17, 2023 and the following terms were used: PD-1, PD-L1, CTLA-4, ICIs, immune checkpoint inhibitor, lung, pulmonary, tumor, cancer, carcinoma, neoplasm, prognostic nutritional index, PNI, survival, prognosis and prognostic.