Purpose: This study was undertaken to assess the antitumor activity and tolerance of chronic oral etoposide (50 mg/m2/d for 21 days every 4 weeks) in metastatic breast cancer (MBC).
Patients and methods: Forty-three consecutive metastatic breast cancer patients with at least one site of measurable disease entered the study. All patients had received prior chemotherapy (adjuvant, three patients; adjuvant plus chemotherapy for metastases, 21; chemotherapy for metastases, 19). Twenty-two and 21 patients had also received prior hormonal and radiation therapy, respectively.
Results: Thirty-five percent of patients (15 of 43; 95% confidence interval, 21% to 51%) had objective responses, according to an intention-to-treat analysis. Responses were seen in lymph nodes (six of 14), skin and soft tissues (eight of 16), lung (six of 14), lytic lesions of the bone (two of six), liver (four of 23), and peritoneum (one of one). The median duration of response was 7 months (range, 3+ to 12). The main toxic side effects were leukopenia (overall, 65% of patients; World Health Organization [WHO] grade 4, 21%), thrombocytopenia (21%; WHO grade 4, 5%) and anemia (51%; WHO grade 4, 5%). Nine patients (21%) required a 25% dose reduction because of myelosuppression, and one patient abandoned treatment because of gastrointestinal toxicity and severe asthenia. Ninety-one percent of patients developed alopecia, 39.5% had mucositis (WHO grade 3, 9.5%) and 60.5% had some degree of emesis (11.5% nausea, 46.5% transient vomiting, 2.5% intractable vomiting). No toxic deaths occurred.
Conclusion: Chronic oral etoposide appears to be an active and well-tolerated regimen in MBC patients previously exposed to chemotherapy. This schedule of etoposide administration warrants further studies, alone or in combination, in MBC.