Etoposide/cisplatin-based chemotherapy for patients with metastatic poorly differentiated carcinoma of unknown primary site

Patients with poorly differentiated carcinoma (PDC) or poorly differentiated adenocarcinoma (PDA) of unknown primary site comprise a sizable minority (25% to 35%) of patients with carcinoma of unknown primary site. Some of these neoplasms are highly responsive to combination chemotherapy, and a minority of patients are curable. Between 1978 and 1982 we treated 67 patients with combination chemotherapy, most of whom received PVB (cisplatin/vinblastine/bleomycin) with or without doxorubicin. Thirty-eight patients (56%) responded to treatment, with 15 (22%) attaining complete responses (CRs). Nine patients (13%) are long-term disease-free survivors. Since that time, we have incorporated etoposide into our treatment program because of its synergism with cisplatin and its marked activity against several other neoplasms including germ cell tumors. Seventeen patients with PDC or PDA of unknown primary site received second-line therapy with etoposide/ cisplatin after failing to respond to PVB. Ten of these patients had partial responses, with a median response duration of 5 months (range, 2 to 12). Eighty-five previously untreated patients with PDC or PDA received etoposide/cisplatin combinations as initial treatment; 57 of 78 evaluable patients (73%) responded to therapy, and 24 (31%) achieved CRs. Sixteen patients (19% of entire group) remain disease-free a median of 28 months (range, 9 to 66) after therapy. Etoposide is active against poorly differentiated carcinoma of unknown primary site. These results indicate that initial treatment with etoposide/cisplatin combinations is equivalent or superior to our previous results with PVB.