Clinical use of Tumor Markers in the Postoperative Management of Breast Cancer Patients: New Concepts

Serial determination of CEA and CA 15.3 in breast cancer follow-up: an assessment of their diagnostic accuracy for the detection of tumour recurrences

We studied the diagnostic accuracy of carcinoembryonic antigen (CEA) and cancer antigen 15.3 (CA 15.3) in detecting breast cancer recurrence. Biomarker follow-up determinations, made over 900 patients, were related to local-regional or distant recurrence using statistical models for longitudinal data. The diagnostic accuracy was quantified in terms of sensitivity, specificity and Youden index. The biomarkers were poorly predictive of local-regional recurrence. As for distant recurrence, the best diagnostic accuracy was obtained considering the two biomarkers jointly and combining two positivity criteria: a value above the normal limit or a difference between two consecutive measurements greater than the critical difference for at least one biomarker. A third criterion, based on within-patient comparison between follow-up determinations and a baseline, failed to improve the above result. CEA and CA 15.3 might play a role in patient monitoring during follow-up for the search of distant recurrence.

Clinical utility of cytokeratins as tumor markers

Cytokeratins, belonging to the intermediate filament (IF) protein family, are particularly useful tools in oncology diagnostics. At present, more than 20 different cytokeratins have been identified, of which cytokeratins 8, 18, and 19 are the most abundant in simple epithelial cells. Upon release from proliferating or apoptotic cells, cytokeratins provide useful markers for epithelial malignancies, distinctly reflecting ongoing cell activity. It appears that motifs in certain cytokeratins make them likely substrates for caspase degradation, and their subsequent release occurs during the intermediate events in apoptosis. The clinical value of determining soluble cytokeratin protein fragments in body fluids lies in the early detection of recurrence and the fast assessment of the efficacy of therapy response in epithelial cell carcinomas. The three most applied cytokeratin markers used in the clinic are tissue polypeptide antigen (TPA), tissue polypeptide specific antigen (TPS), and CYFRA 21-1. TPA is a broad spectrum test that measures cytokeratins 8, 18, and 19. TPS and CYFRA 21-1 assays are more specific and measure cytokeratin 18 and cytokeratin 19, respectively. By following patients with repeated testing during management, the oncologist may obtain critical information regarding the growth activity in symptomatic patients. Although their main use is to monitor treatment and evaluate response to therapy, early prognostic information particularly on tumor progression and metastasis formation is also provided for several types of cancers. Cytokeratin tumor markers can accurately predict disease status before conventional methods and offer a simple, noninvasive, cheap, and reliable tool for more efficient management.

Evaluation of different methods for the detection of minimal residual disease in blood and bone marrow of patients with primary breast cancer: importance for clinical use?

We studied cytokeratin-positive (CK+) cells in the bone marrow (BM) and tumor markers (TM) in the blood of 128 patients with primary breast cancer in order to obtain an early diagnosis of residual disease. CK+ cells of two BM aspirations were detected by immunocytochemistry (IC). To evaluate the usefulness of immunomagnetic separation (IMS) for tumor cell enrichment in clinical samples, IMS was performed prior to IC and compared with the results for IC alone. The overall CK+ rate was 34% (44/128 patients), 29% (15/51) for patients with T1 tumors, 33% (28/84) for N0 patients and 31% (26/82) for patients with G1-2 breast carcinoma. Interestingly, 67% of CK+ patients were only positive in one of the two aspirates studied. A comparison between IC alone and IMS/IC could be performed in 70/128 patients (28/70 CK+). In 6/28 patients, CK+ cells were detected by both methods, in 16/28 patients only by IC and in 6/28 patients only by IMS. At least one TM, including carcinoembryonic antigen, carbohydrate antigen 15-3 and tissue polypeptide antigen, was increased in 58/128 (45%) patients [21/58 (36%) were CK+ in the BM]. Surprisingly, levels for the extracellular domain of Her-2/neu in serum samples were within the normal range in every patient studied. After a 2-year follow-up, 7/128 patients relapsed (3/7 CK+/TM-; 2/7 CK-/TM+; 2/7 CK-/TM-). We conclude that studying two BM aspirates for CK+ cells by IC in combination with TM determination is useful for identifying patients with a higher risk for relapse, however, tumor cell enrichment techniques will have to be improved for clinical use.