Metastatic carcinoma of uncertain primary site: a retrospective review of 57 patients treated with vincristine, doxorubicin, cyclophosphamide (VAC) or VAC alternating with cisplatin and etoposide (VAC/PE).

Background: Metastatic carcinoma of uncertain primary site (CUPS) is a common problem and has a poor prognosis. The intention of this study was to determine whether the addition of cisplatin and etoposide (PE) to vincristine, doxorubicin and cyclophosphamide (VAC) chemotherapy improves outcome.

Methods: Fifty-seven consecutive patients with an initial diagnosis of CUPS were studied. The first 40 patients had received six or 10 cycles of VAC and 17 patients VAC alternating with PE for six cycles. Review of histology using immunohistochemical techniques where appropriate was performed in all cases.

Results: Histologic review resulted in six tumors reclassified as non-Hodgkin's lymphoma (NHL), one as hepatocarcinoma, and one as adenocarcinoma. Six of the 11 responses occurred in patients with a review diagnosis of NHL. If the six cases of NHL and the case of hepatocarcinoma were excluded, there was no difference in survival between VAC and VAC/PE treated patients. Five patients with true CUPS who responded to VAC or VAC/PE had poorly differentiated histology, and this group (n = 24) also had a significantly longer survival.

Conclusions: Some patients thought to have CUPS actually have NHL, and it is this group which responds well to chemotherapy. True CUPS patients respond to chemotherapy only if the tumor is poorly differentiated; survival is significantly longer for this group of patients. An advantage for VAC/PE over VAC chemotherapy was not identified.