Biomarkers have been used by pathologists to aid the diagnosis of tumo
rs for almost three decades. Their use has resulted in the re-evaluati
on and reclassification of several types of tumors, Currently, biomark
ers are required to differentiate certain specific tumors with similar
histologic patterns, Additional uses of biomarkers in the characteriz
ation of neoplastic processes are discussed including their use in pro
gnosis, detecting early neoplastic processes, identifying tumor recurr
ence, measuring the effectiveness of various therapies (surrogate end
point biomarkers), and identifying targets for novel therapies includi
ng immunotherapy and gene therapy, We propose that these newer uses of
biomarkers will be just as important to pathology in the future as th
e uses of biomarkers in diagnosis have been over the past two decades.