Treatable subsets in cancer of unknown primary origin.

The purpose of this study was to investigate the treatable subsets in cancer of unknown primary origin (CUP). Fifty patients (27 males and 23 females; median age, 53 years) with CUP diagnosed between April 1992 and June 1999 were analyzed retrospectively. Of the 50 patients, 39 received chemotherapy: platinum-based in 31, non-platinum-based in 4, and clinical trials of new agents in 4. Of the 39 patients, 13 (33.3%; 95% confidence interval: 19.1 - 50.2%) showed objective responses, with 4 complete responders. Patients with poorly differentiated carcinomas in whom beta-subunit of human chorionic gonadotropin (beta-HCG) was elevated more than 10 mIU / ml and female patients with peritoneal adenocarcinomatosis achieved high response rates (83.3% and 80%, respectively) with platinum-based chemotherapy, as compared with only a 15.3% response rate in the remaining patients. Platinum-based chemotherapy provided promising results in patients with poorly differentiated carcinomas and in female patients with peritoneal adenocarcinomatosis. Significantly elevated serum levels of beta-HCG in patients with poorly differentiated carcinoma might predict a better response to platinum-based chemotherapy. However, the investigation of novel chemotherapeutic approaches is warranted for other groups of patients with CUP.