Prognostic factors in metastatic carcinoma of unknown primary.

From January 1980 to June 1984, 70 patients with metastatic carcinoma of unknown primary treated with combination chemotherapy were analyzed for prognostic factors influencing objective response and survival. Suspicious germ-cell tumors and neuroendocrine tumors were excluded since patients with these malignancies tend to live longer than those with metastatic carcinoma of unknown primary. Objective response rate to combination chemotherapy was 28%. Median survival of all patients responding to combination chemotherapy was better than those not responding (16 v 3 months). In patients with good performance status, median survival was longer in responders than nonresponding patients (17 v 7 months). External lymph nodes or subcutaneous disease as the only site of disease and good performance status favorably influenced both objective response and survival, while the number of different metastatic sites favorably influenced only survival. Neutropenia and thrombocytopenia were appreciable but not fatal or a great cause of morbidity in those with good performance status. Thus, patients with metastatic carcinoma of unknown primary with good performance status or only external nodes or subcutaneous disease should be treated with combination chemotherapy regardless of age, histology, or number of different metastatic sites of disease.