Lung cancer is the number-one cancer killer of both men and women in the United States, killing more than 150,000 people every year. Lung cancer consists of two broad groups: small-cell lung cancers (SCLC), which account for about 25% of bronchogenic carcinomas, and the remaining tumors, non-small-cell lung cancers (NSCLC). SCLC cells possess neuroendrocrine-like properties, whereas most NSCLC lack these functions and can be divided into three major subtypes, adenocarcinoma, squamous cell carcinoma (SCC), and large cell carcinoma (LC). SCLC is one of the most virulent forms of human cancer, characterized by early dissemination and aggressive clinical evolution as compared to NSCLC. The initial responsiveness of SCLC to anticancer drugs and radiation treatment contrasts with the relative resistance of NSCLC to the same types of interventions. The reasons for the differences between SCLC and NSCLC are not fully understood, and one possible explanation may be resistance to killing via programmed cell death or apoptosis.
