Tumor Markers comprise a wide spectrum of biomacromolecules synthesized in excess concentration by a wide variety of neoplastic cells. The markers could be endogenous products of highly active metabolic malignant cells or the products of newly switched on genes, which remained unexprssed in early life or newly acquired
antigens at cellular and sub-cellular levels. The appearance of
tumor marker and their concentration are related to the genesis and growth of malignant
tumors in patients. An ideal
tumor marker should be highly sensitive, specific, reliable with high prognostic value, organ specificity and it should correlate with
tumor stages. However, none of the
tumor markers reported to date has all these characteristics. Inspite of these limitations, many
tumor markers have shown excellent clinical relevance in monitoring efficacy of different modes of
therapies during entire course of illness in
cancer patients. Additionally, determination of markers also helps in early detection of
cancer recurrence and in prognostication.