Biology of small cell lung cancer: an overview

Despite disappointing results in the treatment of small cell lung cancer (SCLC), major progress in our understanding of SCLC biology has occurred in the past decade. Advances in the technique for culturing SCLC tumours in vitro have greatly facilitated the study of the biological properties of this tumour. The major progress in our understanding of SCLC includes: 1) the availability of nonspecific biological tumour markers such as neuron-specific enolase (NSE), the BB isoenzyme of creatine phosphokinase (CPKBB), bombesin/gastrin releasing peptide (GRP) and chromogranin A; 2) the generation of monoclonal antibodies raised against the neural and epithelial features of SCLC tumours; 3) the identification of several autocrine growth factors such as bombesin/GRP, insulin-like growth factor (IGF), transferrin and physalaemin; 4) the close study of cytogenetic abnormalities leading to the discovery of a unique chromosomal deletion of the short arm of chromosome 3 (del 3p 14-21), and to changes in oncogenic expression, e.g. c-myc, L-myc and N-myc, accounting for known biological and treatment results. These data suggest that all lung cancers arise from a common stem cell of endodermal origin. The information derived from these biological studies represents the most promising avenue towards new treatment strategies in SCLC.