Cancer of unknown primary site: review of consecutive cases at the National Cancer Center Hospital of Japan.

Background: Cancer of unknown primary (CUP) is not a rare clinical entity, accounting for 3%-5% of all solid malignancies.

Methods: We retrospectively reviewed 86 (38 male/48 female) patients with a diagnosis of CUP (exclusive of female patients with adenocarcinoma involving the axillary lymph nodes alone and patients with squamous cell carcinoma of the cervical lymph nodes) who were referred to the National Cancer Center Hospital between April 1996 and October 2002.

Results: The median interval between the first visit to a local community hospital and referral to our hospital was 1 month (range, 1 to 45 months). The histological diagnosis was adenocarcinoma in 61 patients (71%), poorly differentiated carcinoma in 18 patients (21%), and squamous cell carcinoma in 4 patients (5%). Twenty-three female patients had peritoneal carcinomatosis of adenocarcinoma. Seventy-eight patients (91%) received platinum-containing chemotherapy. Sixty-one of the 86 patients (71%) were categorized as a subgroup of CUP without a specific therapy, and 55 of these 61 patients (90%) received platinum-containing regimens. The median survivals of all 86 patients and the 61 patients in the subgroup without a specific therapy in this series were 13 months and 11 months, respectively.

Conclusion: In this series, the survival of the patients in the CUP subgroup without a specific therapy did not seem worse than that in previous reports. Empirical chemotherapy with platinum-containing regimens may benefit some CUP patients in a subgroup without a specific chemotherapy.