title: NCCN Clinical Practice Guidelines Occult primary.
abstract: Occult primary tumors, or cancers of unknown primary (CUPs), are defined as histologically proven metastatic malignant tumors whose primary site cannot be identified during pretreatment evaluation. They have a wide variety of clinical presentations and a poor prognosis in most patients. Patients with occult primary tumors often present with general complaints, such as anorexia and weight loss. Clinical absence of primary tumor, early dissemination, aggressiveness, and unpredictability of metastatic pattern are characteristic of these tumors. Life expectancy is very short, with a median survival of 6 to 9 months. In most patients, occult primary tumors are refractory to systemic treatments, and chemotherapy is only palliative and does not significantly improve long-term survival. However, certain clinical presentations of these tumors are associated with a better prognosis. Special pathologic studies can identify subsets of patients with tumor types that are more responsive to chemotherapy. Treatment options should be individualized for this selected group of patients to achieve improved response and survival rates.
authors.forename: David S
authors.initials: DS
authors.lastname: Ettinger
authors.forename: Mark
authors.initials: M
authors.lastname: Agulnik
authors.forename: Justin M M
authors.initials: JM
authors.lastname: Cates
authors.forename: Mihaela
authors.initials: M
authors.lastname: Cristea
authors.forename: Crystal S
authors.initials: CS
authors.lastname: Denlinger
authors.forename: Keith D
authors.initials: KD
authors.lastname: Eaton
authors.forename: Panagiotis M
authors.initials: PM
authors.lastname: Fidias
authors.forename: David
authors.initials: D
authors.lastname: Gierada
authors.forename: Jon P
authors.initials: JP
authors.lastname: Gockerman
authors.forename: Charles R
authors.initials: CR
authors.lastname: Handorf
authors.forename: Renuka
authors.initials: R
authors.lastname: Iyer
authors.forename: Renato
authors.initials: R
authors.lastname: Lenzi
authors.forename: John
authors.initials: J
authors.lastname: Phay
authors.forename: Asif
authors.initials: A
authors.lastname: Rashid
authors.forename: Leonard
authors.initials: L
authors.lastname: Saltz
authors.forename: Lawrence N
authors.initials: LN
authors.lastname: Shulman
authors.forename: Jeffrey B
authors.initials: JB
authors.lastname: Smerage
authors.forename: Gauri R
authors.initials: GR
authors.lastname: Varadhachary
authors.forename: Jonathan S
authors.initials: JS
authors.lastname: Zager
authors.forename: Weining Ken
authors.initials: WK
authors.lastname: Zhen
mesh_terms: D000230:Adenocarcinoma / Q000175:diagnosis / Q000453:epidemiology / Q000473:pathology / Q000628:therapy; D000465:Algorithms; D000906:Antibodies / Q000032:analysis; D000971:Antineoplastic Combined Chemotherapy Protocols / Q000627:therapeutic use; D002277:Carcinoma / Q000175:diagnosis / Q000453:epidemiology / Q000473:pathology / Q000628:therapy; D005260:Female; D006801:Humans; D008207:Lymphatic Metastasis; D008297:Male; D008495:Medical Oncology / Q000331:legislation & jurisprudence* / Q000458:organization & administration; D025202:Molecular Diagnostic Techniques / Q000379:methods; D009382:Neoplasms, Unknown Primary / Q000175:diagnosis / Q000453:epidemiology / Q000628:therapy*; D012955:Societies, Medical / Q000331:legislation & jurisprudence / Q000458:organization & administration; D014481:United States
chemical_list: D000906:Antibodies