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 presentwith CUP syndrome. Median survival for localised disease is 20 and fordisseminated disease, seven months. For localised disease, curativetreatment is more likely and individual therapeutic strategies becomemore important. After conservative diagnostic procedures including MRI,the primary is detected in less than 25%. The diagnostic value ofPET and its influence on therapeutic strategies was evaluated.Patients and methods:Forty-two patients with localised CUPwere investigated from 5 of 98 to 10 of 2000. The presenting site waslymph node metastasis in 34 and visceral metastasis in 8 patients. Aftera median of 7 (3–11) diagnostic procedures without detection ofthe primary, but evidence of localised disease, PET was performed withfluorine-18-fluorodeoxyglucose.Results:In 26 of 42patients (62%), a primary was suggested by PET and confirmed in18 (43%). In 5 of 18 patients beyond localised disease,additional dissemination, not detected by previous diagnostic measures,was diagnosed by PET. Overall, dissemination was only detected only byPET in 16 of 42 patients (38%). In 29 of 42 patients(69%), the PET result influenced selection of the definitivetreatment.Conclusion:In CUP patients, PET has acertain impact on detection of the primary as well as of thedisseminated disease, and may also have a certain impact on therapeuticmanagement.