Chemotherapy in metastatic cancer of unknown primary

textabstractIn general a patient is considered ta have a carcinoma of unknown primary site if na primary tumor ean be identified af ter a thorough history and physical examination, and a reasonabIe laboratory and radiologie work-up. This definition a180 requires a histological diagnosis of carcinoma. The importance of histologie (re)examination in the management of patients with carcinoma of unknown primary site has been emphasized by several authors. Light microscopie examinat ion may al ready provide a clue ta suggest the site of origin. lnununohistochemistry and/or electron microscopy are of additional value, particularly in patients with undifferentiated tumors. A substantial number of patients with a light microscopie diagnosis of anaplastic tumor or undifferentiated carcinoma ultimately prove to have a lymphomas.