Small cell lung cancer.
Lung cancer is the predominant fatal neoplasm of our time, and SCLC, which accounts for about 25% of all lung cancer, if untreated results in death in about 3 months. Currently employed aggressive combination chemotherapy has allowed a 4- to 5-fold improvement in median survival over untreated patients. Ten to 20% of patients with limited disease can be expected to have a long-term (2-yr) survival. The majority of patients, however, have extensive disease. For these patients the median survival is about 7 months. Less than 2% survive 2 yr. During the last 10 yr, experience in the treatment of thousands of patients has been reported. These trials, using a large variety of drug combinations, doses, and schedules as well as multiple modalities including radiotherapy, surgery, and bone marrow transplantation, demonstrate that a plateau has been reached with our present therapeutic approach. The development of new effective therapeutic strategies as well as prevention of SCLC require a better basic understanding of the cellular pathophysiology of the disease. A consistent chromosomal abnormality has been associated with SCLC. This may provide new insight into predisposition and pathogenesis of SCLC. How this chromosomal abnormality relates to loss of control of cell growth is under intense investigation. Similarly, during the past 3 yr, the identification of growth regulatory oncogenes has greatly improved our understanding of malignancy. The discovery that metastatic cells escape immune surveillance has led to attempts at modulating antigenic expression. The modulation of cellular antigenic expression may facilitate the destruction of tumor cells by host defense mechanisms. The understanding of the genetic basis of drug resistance may lead to approaches that prevent or delay resistance. This century has witnessed the emergence of SCLC as an important fatal neoplasm. It has also been during this time that another, formerly dominant pulmonary condition, tuberculosis, has been controlled. The reduction of tuberculosis was accomplished by a combination of scientific understanding, beginning with the discovery of Koch's bacillus, and public health measures. Perhaps a similar parallel for SCLC as well as other forms of cancer will be written. Basic cellular investigations with the new tools of molecular biology as well as measures to control exposure to predisposing environmental factors such as component of cigarette smoke may one day lead to control of SCLC.