Treatment of patients with cancer of an unknown primary site

Cancer of unknown primary (CUP) is a heterogenous group of tumors that accounts for 3 to 5 percent of all malignancies. Due to CUP's heterogeneity, clinical trials are difficult to perform and articles published on the disease require careful interpretation. Among CUP's, there are several clinical groups that are treated with specific treatment modalities. Each clinical group has similar treatment effects and prognoses with common malignancies that arise in adjacent locations, such as breast cancer and head/neck cancer. Therefore, accurate histological diagnosis and careful clinical staging are important. However, many CUP's do not belong to these specific clinical groups and generally have a poor prognosis. The treatment is usually directed based upon histology, location of the tumor, and stage. Platinum agents, taxanes and other new cytotoxic drugs are often used for systemic therapy, but their efficacy is often limited. Currently, specific molecular markers and targeted therapy are being explored.