Cancer of Unknown Primary: Changing Approaches. A Multidisciplinary Case Presentation from the Joan Karnell Cancer Center of Pennsylvania Hospital

Learning Objectives After completing this course, the reader will be able to: Describe the newer pathologic techniques for defining the site of origin of unknown primary cancers, including immunohistochemistry and molecular genetic techniques. List the subsets of patients with unknown primary cancers most likely to achieve long‐term survival with appropriate therapies. Explain how the newer radiologic techniques such as MRI and PET scanning can help to localize unknown primary cancers. Access and take the CME test online and receive 1 hour of AMA PRA category 1 credit at CME.TheOncologist.com Cancer of unknown primary is a common clinical syndrome, accounting for 2%–5% of cancer patients. A representative case is presented. This heterogenous group of disorders includes entities such as poorly differentiated carcinoma of unknown primary, adenocarcinoma of unknown primary, neuroendocrine carcinoma of unknown primary, squamous cell carcinoma of unknown primary, poorly differentiated (not otherwise specified) cancer of unknown primary, and melanoma of unknown primary. It is crucial to identify those treatment‐responsive presentations of unknown primary with the greatest potential for long‐term survival. This discussion emphasizes newer approaches to the diagnosis and treatment of unknown primary cancer, including advances in pathology with immunoperoxidase and molecular genetic techniques, positron emission tomography, and published chemotherapeutic trials. With the increased sophistication of pathologic and radiologic techniques, the frequency of unknown primary cancers will likely continue to decline. Further, as newer and more targeted therapies for specific types of cancer are identified, the previously held nihilism regarding the search for and identification of the primary may become less supportable.