Recent advances in the biology of small cell lung cancer.

Advances in the techniques for culturing human tumors in vitro, especially lung cancer cells, have greatly facilitated studies of the biologic properties of both small cell and non-small cell lung cancer cells. Detailed analysis has been done of well-characterized cell lines of both groups with respect to growth properties, biomarker and antigen expression, cytogenetics, and oncogene amplification and expression. Two major conclusions have emerged from these studies: (1) considerable heterogeneity exists within a given tumor type (eg, SCLC) in the expression of a given biomarker, and (2) overlap in the expression of biomarkers exists between cells of SCLC and non-SCLC, suggesting a common stem cell for all types lung cancer. In the future, clinical trials the impact of the biologic properties of cells on responses to therapy and survival will need assessment.