21-day oral etoposide for metastatic breast cancer - A phase II study and review of the literature

Previous studies of etoposide for metastatic breast cancer commonly used bo lus regimens given over a short period of time and included heavily pretrea ted patients. Results were poor. Chronic oral regimens would be expected to be superior to bolus doses based on pharmacologic studies and patients wit h less previous chemotherapy would be expected to have higher response rate s. We studied the efficacy of oral etoposide at a dose of 50 mg/m(2)/day fo r 21 days of a 28-day cycle in good-risk patients with metastatic breast ca ncer. Healthy patients (Eastern Cooperative Oncology Group performance stat us 0, 1, or 2) who had not received chemotherapy for at least 1 year before study entry were selected for therapy. Thirty-four patients were entered: three patients were ineligible and one was cancelled. Thirty patients were available for analysis of response. One complete response and eight partial responses were documented (response rate, 30%: 95% confidence interval, 15 -49%). A higher response rate was observed in those patients who never rece ived chemotherapy compared with those who had received prior chemotherapy ( 57 vs. 6%, p = 0.004). There were two treatment-related deaths, both owing to myelosuppression and infection. We found long-term administration of ora l etoposide to have a reasonable response rate for metastatic breast cancer (30%). Our response rate was comparable to those of other published studie s of long-term oral etoposide regimens for metastatic breast cancer. Respon se rates in single-arm studies have generally been higher for long-term ora l regimens than those for bolus regimens. We also found the regimen to be s ignificantly toxic, an observation that may be underemphasized in the earli er literature.