Spontaneous regression of small cell lung cancer.

Spontaneous regression of cancers is extremely rare and is associated with specific malignancies. Spontaneous regression of bronchogenic lung cancer has rarely been reported, and regression of small cell lung cancer is even less common. Such regression is generally ascribed to immunological factors but is not well understood. This case report describes a patient with spontaneous regression of small cell lung cancer that has persisted for 11 years and considers possible mechanisms.