Prognostic factors in cancer of unknown primary site

Aims and background. Patients with cancer of an unknown primary site (CUP) usually have a poor outcome. The identification of prognostic factors that affect survival can help clinicians find a better approach to such cases in terms of diagnostic and therapeutic management. Methods. We conducted a retrospective study including the cases of CUP recorded at the University Hospital 12 de Octubre Tumor Registry between 1999 and 2003. Results. CUP was diagnosed in 265 patients during the analyzed period. One hundred and seventy-one were men (64.5%) and the mean age of the patients was 66.9 years (range 32-98 years). The median survival was 2.5 months, and the survival rate was 35.1% 6 months from diagnosis (95% CI: 28.9-41.3) and 24.5% 1 year from diagnosis (95% CI: 18.7-30.3). Univariate analysis revealed as significant predictive variables of a better outcome age under 70 years; involvement of a single organ; normal serum levels of alkaline phosphatase and albumin; normal erythrocyte sedimentation rate; normal levels of the serum tumor markers CEA, CA 19.9 and CA 15.3; squamous carcinoma histology; clinical presentation as lymph node enlargement; and the administration of treatment. Multivariate analysis showed that albumin and alkaline phosphatase levels, squamous carcinoma histology, age and treatment were the most important prognostic factors. Other variables analyzed (liver, bone or lung involvement, lactate dehydrogenase levels, gender) did not affect survival. Conclusions. CUP has a poor prognosis. Some prognostic factors that affect survival in these patients, however, may be identified.