Abstract
In 65 patients with systemic breast cancer, a biochemical response index using three tumour markers in combination, carcinoembryonic antigen (CEA), carbohydrate antigen 15-3 (CA 15-3) and erythrocyte sedimentation rate (ESR), allowed objective biochemical assessment of response to endocrine therapy. Changes in these three markers at 2, 4 and 6 months showed a highly significant correlation with UICC assessed response at 6 months. At 4 months, changes in these three markers resulted in a selectivity of 93%, with a sensitivity of 92% and a specificity of 82%. Survival of groups of patients assessed biochemically or by UICC criteria for non-progression or progression showed no significant difference. The advantage of the biochemical assessment are that it is objective and reproducible. The assessment gives similar information to the UICC assessment but can be carried out earlier. Changes in the three markers appears to reflect the dynamics of change in tumour mass in response to systemic therapy in contrast to the UICC criteria which reflect structural change.
Highlights
In Nottingham we have previously shown in a retrospective analysis (Williams et al, 1990) and prospectively confirmed (Robertson et al, 1990), that changes in serum carcinoembryonic antigen (CEA) and erthrocyte sedimentation rate (ESR) individually correlate with therapeutic response in patients with metastatic breast cancer
In analysing the correlation between biochemical marker movement after 2, 4 or 6 months therapy and Union Against Cancer (UICC) assessed response we combined the categories of complete response (CR), partial response (PR) and static disease (SD) into 'non-progressive' disease group and compared this with the group of patients showing progression
Biochemical assessment of response Biochemical response to therapy in patients with metastatic breast cancer is assessed in the same manner for all serum markers studied in this unit - i.e. any change in marker while the patient is on therapy is related to the pre-treatment baseline value of the marker and the interassay coefficient of variation (CV) of the marker (10% for all three markers in this study)
Summary
Assessment of responseClinical assessment of response Patients with metastatic breast cancer were assessed by UICC criteria prior to commencing anticancer therapy and after 2, 4 and 6 months therapy or between these times if clinically indicated. As recommended by the British Breast Group (1974) patients were classified as showing complete or partial response or static disease (no change) only where the minimum duration of response or static disease was 6 months. In analysing the correlation between biochemical marker movement after 2, 4 or 6 months therapy and UICC assessed response we combined the categories of complete response (CR), partial response (PR) and static disease (SD) into 'non-progressive' disease group and compared this with the group of patients showing progression. Patients who started with an initially elevated value which fell to below the cut-off level or patients with an initial value above the cut-off level which subsequently decreased by more than the interassay CV (10%) for that particular marker were regarded as showing a decreasing marker level indicative of 'biochemical response'. Patients with an initial pretreatment value below the cut-off level which subsequently rose above the cut-off level or patients with an initial value above the cut-off
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