Serum tumour markers in lung cancer: history, biology and clinical applications.

The association of biological markers with cancer has been recognized for many decades. Current interest in markers for cancer arose in the mid 1960s, with the discoveries of alpha-fetoprotein and carcinoembryonic antigen. They were called oncofetal proteins, because of their presence in high concentrations during embryonic development, their virtual disappearance in the neonatal period, and their reappearance with cancers of specific cell types. Essentially, any molecular species may be produced in abnormal amounts or under abnormal circumstances by a tumour, and thereby become useful as a tumour marker. Several tumour markers have been studied in lung cancer. Unfortunately, none of these appear to be sufficiently sensitive and specific to be reliable for screening and diagnostic purposes. However, there is a body of evidence which proves that at least some of these substances may be useful in the evaluation of the course and prognosis of the disease. This review presents data concerning the most studied and interesting tumour markers in lung cancer.