Poorly differentiated carcinoma or adenocarcinoma of unknown primary site: long-term results with cisplatin-based chemotherapy.

Cases of poorly differentiated carcinoma and poorly differentiated adenocarcinoma of unknown primary site represent a large minority of patients with carcinoma of unknown primary site and are clinically distinct in several ways from well-differentiated adenocarcinoma. Cisplatin-based combination chemotherapy produces meaningful clinical responses in more than 50% of the poorly differentiated histologies, and there is a potential for cure in some of these patients (10% to 15%). Clinical and pathologic features enable us to identify many of the patients with responsive tumor types. It is hoped that the future will brighten for these patients as the prospects of genetic diagnosis and treatment become more realistic, and the therapy of common epithelial neoplasms becomes more successful.