Extended-Schedule Oral Etoposide in Selected Neoplasms and Overview of Administration and Scheduling Issues

Abstract

Extended schedules of oral etoposide have been evaluated in many types of advanced cancer. In addition to their use in the common solid tumours, extended schedules have been employed in Kaposi’s sarcoma (both AIDS-related and endemic types), medulloblastoma, glioma, and hepatocellular carcinoma. Single agent activity was demonstrated in all of these tumour subtypes. For patients with carcinoma of unknown primary site, we have recently incorporated a 10-day oral etoposide schedule into a combination regimen that also includes paclitaxel and carboplatin. With this regimen we achieved a 47% response rate in a group of 53 evaluable patients, with a median survival of 13.4 months. Patients with adenocarcinoma and poorly differentiated carcinoma of unknown primary site had comparable response rates and survival. According to a large number of clinical trials and pharmacokinetic data, a daily oral etoposide dose of 50 mg/m² consistently produces serum concentrations >1 mg/L for several hours each day. Lower doses fail to consistently produce this serum concentration, which is considered necessary for optimum tumoricidal activity. Optimal dose duration is 10 to 14 days, particularly when combination regimens are being employed. Oral etoposide has an established role as a single agent in patients with low grade non-Hodgkin’s lymphoma, Kaposi’s sarcoma, and testicular cancer (if residual carcinoma is resected after first-line treatment). The optimal use of extended-schedule etoposide in combination regimens is not defined but is being evaluated in a number of etoposide-sensitive malignancies.