[Lung cancer].

Tumor markers are defined as substances which are produced by cancer cells or non-cancer cells reactive to cancer cells, and reflect the cancer status, such as its presence, characteristics, and volume. Clinically, many tumor markers are useful not only to assess the presence/absence of cancer, the primary site, histology, stage, and recurrence, but also to monitor the anti-cancer therapy. Tumor markers for lung cancer play only supporting roles because of their limited sensitivity and specificity, but they are clinically essential to daily medical oncology. This review addresses 6 important tumor markers for lung cancer, namely, CEA, SLX, CYFRA, SCC, ProGRP, and NSE.