NY-ESO-1 is another well-characterized CT antigen that appears to be the most immunogenic CT antigen known to date. Integrated humoral and cellular immune response against NY-ESO-1 are frequently observed in patients with tumors with NY-ESO-1 expression. As a member of CT antigens, NY-ESO-1 is expressed in a variety of malignant neoplasms, including melanomas, and esophageal, breast, prostate, urinary tract, ovarian, and lung cancers. Recently, immunohistochemical and molecular analytical approaches for the detection of NY-ESO-1 expression were compared, defining the reliability of each method. However, its clinical significance, e.g. in prognosis, in lung cancer is unclear.