Abstract

PURPOSE
For malignant diseases, predictions about tumor behavior and determination of appropriate therapy are based on the primary tumor sites, but 2-9% of cancer patients are diagnosed without identifiable primary tumor sites. Metastatic tumors of unknown primary origin (MUO) are a heterogeneous group of tumors with variable natural histories. The majority of these patients fall outside of treatable subjects and seldom respond to therapy. To define further the natural history of MUO and identify prognostic factors, we undertook a clinical analysis of 141 consecutive patients with a presumed diagnosis of MUO.
MATERIALS AND METHODS
One hundred forty-one patients were diagnosed with unknown primary tumor from Jan. 1, 1992 through Aug. 31, 1995. The primary end point for the study was survival, which was calculated from the first day of patient registration diagnosed histologically. The survival curves were estimated using the Kaplan-Meier method and compared using the log-rank test. To identify important prognostic factors, univariate and multivariate analyses were conducted.
RESULTS
Most of the 141 patients had histologic or cytologic evidence of adenocarcinoma and had more than one site metastatically involved. The predominant sites of tumor involvement were lymph node, peritoneum, bone, liver, lung, and pleura. Univariate and multivariate analyses identified numerous important prognostic factors with a significant influence on survival, including performance status (P 0.0001), specific organ sites involved (lung P 0.0076 or liver P 0.0310), and chemotherapy group (P- 0.0480).
CONCLUSION
This study validated clinical courses and important prognostic factors that had an impact on survival in MUO.

• Keywords: Metastatic tumor of unknown primary;Prognostic factors