Cancer of unknown primary site

Cancer of unknown primary is a clinical challenge that occurs in about 10% of the cancer patients. The major goal is to identify curable patients, while unnecessary efforts and discomfort should be avoided in intreatable patients. Extensive radiological examinations and serum tumour markers have turned out to be unsatisfactory means to establish the origin of the metastasis in patients with cancer of unknown origin. The crucial step for precise diagnosis is histopathological examination of the malignant tissue. Transmission electron microscopy and immunocytochemistry and genetic analysis are being increasingly used in the diagnostic evaluation of patients with cancer of unknown primary. Once a diagnosis is strongly suggested, specific treatment can be administered according to treatment in advanced known cancer. While regional disease is amenable to surgery and/or radiation therapy, multimodality treatment should be considered in treatable disseminated disease. Subsets of patients with a favourable prognosis include non-Hodgkin's and Hodgkin's lymphoma, germ cell tumours and thyroid cancer. A fair response to combination therapy can be expected in breast, ovarian and prostate cancer, while metastatic gastrointestinal or urogenital tumours remain difficult to treat. If it is not possible to identify the primary, empiric chemotherapy may provide a chance for cure in about 5% of the cases. The most common regimen employs 5-fluorouracil, adriblastin and mitomycin C. All in all, the prognosis of patients with the CUP-syndrome remains poor--the median survival in somewhat less than six months.