The current understanding of the biology and molecular biology of lung cancer pathogenesis and progression is reviewed. Awareness of the influence of growth factors, oncogenes, and tumor suppressor genes as well as signal transduction and angiogenesis pathways on the natural history of cancer cells has led to attempts to develop new therapeutic strategies directed at interrupting tumor cell growth. Treatments utilizing monoclonal antibodies, matrix metalloproteinase inhibitors, and gene transfer and alteration are currently being investigated. The rationale and effectiveness of these treatments in early trials are explored, and recommendations for future directions in cell biology research are presented. Interest in the biology and molecular biology of tumor cells has led to some important findings that may provide opportunities for new treatments. Several of these new directions for anticancer therapy are already being examined in phase I clinical trials.