Management of cancer of unknown primary

Cancer of an unknown primary site is most commonly an aggressive metastatic tumor with a median patient survival of 6 to 9 months. Histologically, it is predominantly adenocarcinoma, and if the primary site is subsequently diagnosed, it is usually the pancreas or lung. Biopsy should be performed whenever possible to classify a tumor of unknown primary origin into one of the following entities: adenocarcinoma, poorly differentiated carcinoma with characteristics similar to adenocarcinoma, squamous cell carcinoma, neuroendocrine carcinoma, poorly differentiated neoplasm. After determining the primary tumor type, the subtype is determined by immunohistochemical staining. In oligometastatic disease, there is a possibility of surgical treatment. Radiotherapy is used as a part of combined modality treatment. Most patients with cancer of unknown primary have an unfavorable prognosis despite multiple chemotherapy agents, and no protocol can be recommended as standard therapy.