RT Journal Article T1 2018 consensus statement by the Spanish Society of Pathology and the Spanish Society of Medical Oncology on the diagnosis and treatment of cancer of unknown primary. A1 Losa, F A1 Iglesias, L A1 Pané, M A1 Sanz, J A1 Nieto, B A1 Fusté, V A1 de la Cruz-Merino, L A1 Concha, Á A1 Balañá, C A1 Matías-Guiu, X K1 Biopsy K1 Cancer of unknown primary K1 Chemotherapy K1 Diagnosis K1 Histopathology K1 Immunohistochemistry K1 Molecular pathology K1 Prognosis AB Cancer of unknown primary (CUP) is defined as a heterogeneous group of tumours that present with metastasis, and in which attempts to identify the original site have failed. They differ from other primary tumours in their biological features and how they spread, which means that they can be considered a separate entity. There are several hypotheses regarding their origin, but the most plausible explanation for their aggressiveness and chemoresistance seems to involve chromosomal instability. Depending on the type of study done, CUP can account for 2-9% of all cancer patients, mostly 60-75 years old. This article reviews the main clinical, pathological, and molecular studies conducted to analyse and determine the origin of CUP. The main strategies for patient management and treatment, by both clinicians and pathologists, are also addressed. YR 2018 FD 2018-05-28 LK http://hdl.handle.net/10668/12514 UL http://hdl.handle.net/10668/12514 LA en DS RISalud RD Apr 5, 2025