CYFRA-21-Lung-Cancer-Marker is a useful test to detect reappearance of lung cancer in an already diagnosed patient. Tumor marker test allows a doctor to diagnose cancer and plan a treatment. CYFRA-21 is a handy marker in the management of Non-Small Cell Carcinoma Lung (NSCCL). 85% of lung cancers are detected as NSCCL. The test has the tendency to show positivity in certain cases of Squamous cell carcinoma, large cell carcinoma and Adenocarcinoma.