Extrapulmonary manifestations of tumors of the lung

Lung tumors, among other, secrete substances which are identical to or which mimic the activities of conventional hormones. These ectopic tumor secretions appear to be anarchistic and beyond the control of mechanisms regulating normal endocrine physiology. Despite the relative inefficiency of these tumors as endocrine organs, production of sufficient quantities of the substance, exceeding those from normal sources, results in recognizable ectopic endocrinopathies. The association of certain tumor cell types with specific hormonal patterns (Cushing syndrome with oat cell; hypercalcemia with squamous cell) is considered consistent with the concept of genetic derepression.