Opportunities and challenges of immune checkpoint inhibitors for extensive-stage small-cell lung cancer

Small-cell lung cancer (SCLC) accounts for 15%-20% of primary lung cancers, and it is characterized by low differentiation, rapid proliferation, and early metastasis. At least two-thirds of SCLC patients present with the extensive stage (ES) at the time of initial clinical diagnosis. Over the last 2 decades, platinum-based combination chemotherapy has remained the standard first-line treatment for SCLC. With the introduction of the immunotherapy era, immunotherapy plus chemotherapy has replaced conventional chemotherapy as the first-line treatment option for ES-SCLC and is recommended by National Comprehensive Cancer Network clinical guidelines. Therefore, in this review, we present the latest research advances in SCLC treatment, predictive biomarkers, and other topics of high interest to provide options for patients with SCLC.