Abstract: The primary focal area of carcinoma of unknown primary (CUP) can not be determined by clinical examination. It is difficult to find the primary site and its prognosis is poor. The traditional diagnostic approaches mainly include pathological examination, endoscopy, imaging technology and so on. However, positron emission tomography is the preferred approach. In recent years, gene expression profiling has become a new diagnostic approach to find the source of CUP. The detection rate by gene expression profiling is high, and the approach can accurately identify the primary site. The recommended therapies include classic platinum or paclitaxelbased chemotherapy, radiotherapy or surgery, and sitedirected therapy by gene expression profiling for patients with CUP improves their survival rate.

Key words: Neoplasms, unknown primary, Gene expression profiling, Diagnosis, Therapy