Paraneoplastic syndromes in lung cancer.

Paraneoplastic syndromes are caused by factors produced by cancer cells that often act at a site distant from both the primary site and its metastases. These syndromes are estimated to occur in only 7% to 15% of patients with cancer and are diagnoses of exclusion. If the definition of paraneoplastic syndrome is broadened to include indirect effects of the tumor such as cachexia or the anemia of chronic disease, the incidence is much higher. Lung cancer, particularly small cell lung cancer, is the most common malignancy causing paraneoplastic syndromes. This review focuses on recently published literature on paraneoplastic syndromes associated with lung cancer, including humoral hypercalcemia of malignancy, autoimmune paraneoplastic neurologic syndromes, neuromuscular disorders, and cancer cachexia. It includes advances in both molecular biology and immunology, and in clinical investigation.