Used for Supporting  diagnosis of  Non-Small-Cell Lung Cancer (NSCLC). Cyfra21-1 belongs to a cytokeratin family, which is normally expressed in epithelial tissues and forms the epithelial cells’ filament cytoskeleton and it can be used as a circulating tumor marker. Although expressed in all body tissues, its major occurrence is in the lung, particularly in lung cancer tissues, so it is a sensitive, specific, and valuable biomarker for estimation of diagnosis, prognosis, and therapy monitoring of non-small-cell lung cancer (NSCLC), especially of squamous cell subtype.