Cisplatin-based combination chemotherapy in the treatment of poorly differentiated carcinoma and poorly differentiated adenocarcinoma of unknown primary site: Results of a 12-year experience

Purpose: We previously reported excellent responses to cisplatin-based chemotherapy in a minority of patients with poorly differentiated carcinoma (PDC) or poorly differentiated adenocarcinoma (PDA) of unknown primary site. We have continued to study and to treat these patients, and now report clinical characteristics, treatment results, and prognostic factors in a large group of patients identified prospectively. Patients and Methods: Between February 1978 and December 1989, we treated 220 patients with PDC or PDA of unknown primary site. The median age was 39 years; 48% of patients had predominant tumor location in the mediastinum, retroperitoneum, or peripheral lymph nodes. Specialized pathologic studies resulted in the identification of specific tumor types in only a few cases. All patients received cisplatin-based chemotherapy; between 1978 and 1984, 116 patients received cisplatin, vinblastine, and bleomycin (PVeB) ± doxorubicin, and 104 patients treated since January 1985 received cisplatin and etoposide ± bleomycin. Results: One hundred thirty-eight patients (63%) had objective responses to therapy, and 58 (26%) had complete response. Thirty-six patients (16%) are currently disease-free at a median of 61 months following therapy (range, 11 to 142 months). Actuarial 10-year survival is 16%. Favorable prognostic factors identified by Cox regression analysis include: (1) predominant tumor location in the retroperitoneum or peripheral lymph nodes, (2) tumor limited to one or two metastatic sites, (3) no history of cigarette use, and (4) younger age. Conclusion: Patients with PDC or PDA of unknown primary site represent another group of patients for whom potentially curative therapy is available. Patients with this syndrome should be distinguished from patients with well-differentiated adenocarcinoma of unknown primary site, and should receive a trial of cisplatin-based chemotherapy.