Phase II study of oral administration of etoposide for patients with well- and moderately-differentiated adenocarcinomas of unknown primary site

Abstract

Background: The prognosis of patients with well- and moderately-differentiated adenocarcinomas of unknown primary is poor, as a consequence of chemotherapy resistance.

Patients and methods: We performed a phase II study with prolonged oral administration of etoposide in 25 chemotherapy-naive patients with well- and moderately-differentiated adenocarcinomas of unknown primary site. The treatment regimen was 50 mg/m2 for 21 days, every four weeks.

Results: Of 24 evaluable patients, two achieved partial responses (8%) lasting 15+ and 17 months, 11 patients had stable disease, and 11 progressed during treatment. The major toxicity was myelosuppression. WHO grades 3 or 4 leukocytopenia was seen in six patients but confined to the first treatment cycle in five of them. Four of these latter five patients already had disease progression after one treatment cycle. A primary tumor site was later identified in four patients, three colon carcinomas and one carcinoma of the pancreas.

Conclusion: Etoposide given in this dose and schedule has only limited activity in patients with well- or moderately-differentiated adenocarcinomas of unknown primary site.