[Metastatic cancers of unknown primary site]

It is relatively common to observe metastatic cancer of unknown origin. In approximately 20% of the cases, the primary cancer is later identified during the lifetime of the patient. In others, even necropsy does not reveal the origin. The most frequently identified origins are pancreas or bronchogenic cancer. Initially search is guided by the pathology report of the tumor: well-differentiated adenocarcinoma (60% of the cases), squamous cell cancer (5-10% of the cases), undifferentiated cancer (1/3 of the cases). Immunoperoxydase tumor staining is indispensable to detect specific tumors (1/5 of the cases). Subgroups of adenocarcinomas have been distinguished as for squamous cell carcinoma of unknown origin allowing specific treatment and better results. Recent reports on undifferentiated cancers have demonstrated their increased sensitivity to cisplatin-based chemotherapy. Prognosis remains poor, nevertheless, mean survival does reach approximately one year. Progress has been especially achieved in individualized groups. Chemotherapy remains the basic treatment.