[Small cell lung cancer heterogeneity and molecular subtypes: biological and clinical relevance]

Small-cell lung cancer (SCLC) is a highly aggressive malignancy characterised by genomic instability and early metastatic spread. Patients are typically diagnosed at advanced disease stage, when platinum-based chemotherapy with immunotherapy represents the standard therapeutic approach. The role of radiotherapy with concomitant systemic therapy is also well established in the management of SCLC patients. Although these therapeutic approaches are initially effective, most patients rapidly develop resistance. This clearly highlights the need to improve therapeutic efficacy and broaden the scope of current therapeutic strategies. Recent advances in the study of this disease, once considered homogeneous, have led to a new model of the SCLC classification scheme based on the relative expression of certain transcriptional regulators and inflammatory characteristics. New biological insights into the molecular subtypes of SCLC could lead to the implementation of subtype-specific therapeutic approaches. Here, we summarise our key findings concerning the biological and clinical relevance of SCLC molecular subtypes.