Tumor markers: the potential of "omics" approach

Tumor markers are the molecules that indicate the presence or prognosis of malignancy. Most often, tumor markers are produced by the cancer tissue itself. Many of them could be secreted into the body fluids in small quantities. Thus, tumor markers could be useful for early diagnostics of primary tumors and relapsed disease, as well as for determining tumor prognosis and predicting likely response of the tumor to therapy. Tumor markers are part of the clinical routine. Nevertheless, lack of sensitivity and specificity precludes routine usage of single tumor markers in population-based screening. Shortcomings of single tumor markers could be solved by parallel evaluation of multiple tumor markers that can perform with required certainty. Genome and proteome-wide approaches currently lead to identification and initial characterization of hundreds new tumor marker candidates. Most prominent of such methods are serological analyses of recombinant cDNA expression libraries (SEREX), 2-dimensional polyacrylamide gel electrophoresis, mass spectrometry, as well as protein and DNA microarrays. Last but not the least is a computational approach allowing high-throughput detection of tumor marker candidate genes in publicly available datasets. Listed approaches are critically discussed in this review as well as the most crucial tumor-related findings. Finally, a perspective on the future of tumor markers in the tailored medicine is given.