CLINICAL UTILITY AND VALIDATION OF EMERGING BIOCHEMICAL MARKERS FOR MAMMARY ADENOCARCINOMA

The clinical utilities of the emerging biochemical markers for mammary adenocarcinoma CA 15-3, CA 549, CA M26, CA M29, and MCA (mucin-like c arcinoma-associated antigen) were assessed by a formal rating accordin g to six desirable marker characteristics. All five indicators similar ly have good specificities but limited sensitivities. As a consequence , these markers mainly meet just two desirable criteria: their frequen cy and degree of expression reflect tumor burden and prognosis, and th ey may correlate with therapeutic results. The validation of these ass ay properties by clinical trials was evaluated by another rating syste m, designed to assess proband sample selection, restrictions on allowa ble observations, and choice of statistical descriptors. By these benc hmarks, the estimates of the prior probabilities of test outcome (sens itivity and specificity) are reasonably definitive, but conclusive jud gments about the posterior probabilities of test outcome (''predictive values'') and about values and costs associated with testing are not possible. Three approaches to enhance the limited clinical utility of biochemical breast cancer markers are considered: shifts of the diagno stic decision threshold, marker panels, and sequential testing. Howeve r, none of these strategies improves the described performance charact eristics.