[Biological tumor markers].

The classification of tumor markers can at present be only provisional since in this field new acquisitions are reported daily. Nevertheless, during the last few years, a number of monographs and chapters in oncology texts have become available for students and physicians in which certain parameters (sensitivity, specificity, predictive value of individual markers) are illustrated, thus allowing for a more accurate evaluation of their diagnostic efficacy and offering indications as to which of these markers are most useful in relation to the site of the tumor. Although tumor markers are present throughout the organism, the above review is limited to those found in blood. Clinical results obtained to far have already lead to the conclusion that tumor markers are useful above all for the diagnostic and therapeutic follow-up of patients rather than for the diagnosis of tumors. The present tendency is for the association of several markers since a higher percentage of positive results is achieved both for diagnostic purposes and for the detection of residual foci after apparently successful treatments and for the precocious detection of recurrences, as well as for the evaluation of the efficacy of ongoing therapies.