Localised disease in cancer of unknown primary (CUP): The value of positron emission tomography (PET) for individual therapeutic management

Background: Two to four percent of cancer patients present with CUP syndrom e. Median survival for localised disease is 20 and for disseminated disease , seven months. For localised disease, curative treatment is more likely an d individual therapeutic strategies become more important. After conservati ve diagnostic procedures including MRI, the primary is detected in less tha n 25%. The diagnostic value of PET and its influence on therapeutic strateg ies was evaluated. Patients and methods: Forty-two patients with localised CUP were investigat ed from 5 of 98 to 10 of 2000. The presenting site was lymph node metastasi s in 34 and visceral metastasis in 8 patients. After a median of 7 (3-11) d iagnostic procedures without detection of the primary, but evidence of loca lised disease, PET was performed with fluorine-18-fluorodeoxyglucose. Results: In 26 of 42 patients (62%), a primary was suggested by PET and con firmed in 18 (43%). In 5 of 18 patients beyond localised disease, additiona l dissemination, not detected by previous diagnostic measures, was diagnose d by PET. Overall, dissemination was only detected only by PET in 16 of 42 patients (38%). In 29 of 42 patients (69%), the PET result influenced selec tion of the definitive treatment. Conclusion: In CUP patients, PET has a certain impact on detection of the p rimary as well as of the disseminated disease, and may also have a certain impact on therapeutic management.