Purpose: To evaluate the toxicity, response rate and short-term survival associated with the chemotherapy combinations of docetaxel plus cisplatin or carboplatin when used for the treatment of patients with metastatic carcinoma of unknown primary site.
Patients and methods: Twenty-six patients were treated with docetaxel 75 mg/m2 i.v. and cisplatin 75 mg/m2 i.v. given every three weeks (study A) and subsequently, 47 patients were treated with docetaxel 65 mg/m2 and carboplatin (AUC dose = 6) every three weeks (study B). Stable or responding patients received a maximum of eight courses of therapy. Patients who were known to be in treatable subset groups were excluded from these trials. The majority of patients had two or more sites of metastasis; about 45% had adenocarcinoma and 50% poorly differentiated carcinoma.
Results: In study A, 6 of 23 (26%) assessable patients had a major response to therapy. The median survival was eight months and one-year survival 42%. Seven patients were removed from the study early for grade 3 or 4 nausea and vomiting. In study B, 9 of 40 assessable patients (22%) had a major response to therapy. Median survival was eight months and one-year survival 29%. Toxicity associated with this regimen was predominantly myelosuppression. Comparisons of the two sequential trials showed no differences in response rates or survivals (P = 0.75).
Conclusions: Docetaxel and cisplatin (study A) is an active combination in carcinoma of unknown primary site, but associated with substantial gastrointestinal toxicity. A combination of docetaxel plus carboplatin (study B) is better tolerated and produced a similar response rate, median survival and one-year survival. Comparative phase III trials will be necessary to unequivically prove a survival advantage for any form of therapy in these patients. However, the survival for patients with carcinoma of unknown primary site receiving docetaxel-based chemotherapy is comparable to the survivals for several other groups of advanced cancer patients, such as non-small cell lung cancer, receiving various types of chemotherapy.