Carcinoma of unknown primary site: treatment with 1-hour paclitaxel, carboplatin, and extended-schedule etoposide

To evaluate the efficacy and toxicity of a novel chemotherapy combination that includes paclitaxel, carboplatin, and extended-schedule etoposide in the treatment of patients with carcinoma of unknown primary tumor site.

Fifty-five patients with carcinoma of unknown primary tumor site were treated with the following regimen, administered every 21 days: paclitaxel 200 mg/m2 by 1-hour intravenous (I.V.) infusion on day 1, carboplatin at an estimated area under the concentration-time curve (AUC) of 6.0 on day 1, and etoposide 50 mg alternated with 100 mg orally on days 1 through 10. Responding patients received a total of four courses of treatment. The following histologies were included: adenocarcinoma, 30 patients; poorly differentiated carcinoma (PDC) or poorly differentiated adenocarcinoma (PDA), 21; poorly differentiated neuroendocrine carcinoma, three; and squamous carcinoma, one.

Twenty-five of 53 assessable patients (47%; 95% confidence interval [CI], 33% to 61%) had major objective responses to treatment (seven complete responses). Response rates were similar in patients with adenocarcinoma versus PDC (45% and 48%, respectively). The actuarial median survival time for the entire group was 13.4 months. The regimen was well tolerated, with only seven hospitalizations for treatment of neutropenia and fever (4% of courses) and no treatment-related deaths.

The combination of paclitaxel, carboplatin, and extended-schedule etoposide is highly active and well tolerated in patients with carcinoma of unknown primary tumor site. Response rates and survival in this multicenter community-based trial compare favorably with all previously studied empiric regimens. In addition, this regimen is substantially less toxic and easier to administer than the cisplatin-based regimens previously used in this setting. If this level of efficacy is confirmed, this treatment should be considered standard first-line therapy in patients with carcinoma of unknown primary tumor site.