Small cell lung cancer; recent advances of its biology and therapeutic perspective

Lung cancer is historically divided into two major categories: small cell lung cancer (SCLC) and non-small cell lung cancer (NSCLC). While the therapeutic efficacy of NSCLC has improved due to the development of molecular targeted therapy and immune checkpoint inhibitors (ICIs) treatment, there has been very slow progress in the therapeutic advances of SCLC. Since SCLC is a deadly disease with rapid progression and early metastasis and comprises approximately 10% of lung cancer cases, more attention should be given to the therapeutic strategy for SCLC. Most SCLC cases respond to cytotoxic drugs, cisplatin, and etoposide. The objective response rate to the standard regimen is reported to be approximately 70% that is sufficient as standard therapy. However, almost all tumors recur and become refractory to chemotherapy which is the most important problem of this deadly disease. Recently, for the first time in several decades, ICIs have changed the standard therapy for SCLC. It must be emphasized that although ICIs paved the new way for SCLC therapy, more precise and effective therapy for SCLC is desired. Unfortunately, precise molecular mechanisms of SCLC are yet to be understood. Recent elaborate studies on the cell biology of SCLC uncovered several important aspects of molecular mechanisms. Gene profiling of cancer cells can be done using modern technology like next-generation sequencing (NGS). In this minireview, we describe the advances of modern technology in SCLC research and consider future therapeutic strategies based on the molecular mechanisms of SCLC.