)Tumor markers* Just an adjunct to diagnosis, and establishing a diagnosis on the basis of tumor markers alone (especially a single result) is associated with pitfalls because of the problem of non-specificity.* Clinical uses can be broadly classified into 4 groups: screening and early detection, diagnostic confirmation, prognosis and prediction of therapeutic response and monitoring disease and recurrence.* Serum levels, in certain situations, can be used in staging, prognostication or prediction of response to therapy.* Monitoring disease is, perhaps, the most common clinical use of serum tumor markers.* Rising trend in serum levels may detect recurrence of disease well before any clinical or radiological evidence of disease is apparent ("biochemical recurrence").">