The use of blood tumour markers in the monitoring of metastatic breast cancer unassessable for response to systemic therapy

The role of blood tumour markers is established in the monitoring of response to systemic therapy for patients with metastatic breast cancer assessable by UICC criteria. This paper examines the use of marker measurements (in the form of a previously devised biochemical index score comprising CA15.3, CEA and ESR) in patients with metastatic lesions unassessable for response by UICC criteria. Of 218 patients with metastatic breast cancer treated over a 2-year period in the Nottingham Breast Unit, 43 patients (20%) had unassessable disease and 36 of them with blood marker results available were studied. Eighty-six per cent of patients were biochemically assessable. All patients who achieved biochemical response remained unassessable by UICC criteria. Twenty-two patients progressed initially or subsequently (after an initial biochemical response), either biochemically or by UICC criteria. Biochemical assessment completely paralleled UICC assessment in all eight patients who progressed by both assessments. Biochemical progression occurred ahead of UICC assessment in four of them with a median lead-time of 4.5 months. Biochemical assessment by blood tumour markers is useful in patients with metastatic breast cancer unassessable for response to systemic therapy. These findings need to be confirmed in a larger patient series.