Bedeutung der positronenemissionstomographie (PET) für die behandlung von patienten mit unbekanntem primärtumor (CUP)

Background: In patients with cancer of unknown primary median survival for localized disease is 20, for disseminated disease 7 months. After diagnostic procedures including MRI or endoscopy, the primary tumor is detected in less than 25%. In the study presented here the value of PET for detection of the primary tumor and a possible dissemination has been investigated and related to therapeutic regimens. Patients and Methods: Between May 1998 and February 2001 a total of 52 patients with CUP syndrome, 18 females and 34 males, have been included. At first diagnosis, stage of disease was localized in 43 patients (35 lymphonodal, eight visceral), and disseminated in nine patients (Table 1). After a median of seven (range three to eleven) diagnostic procedures without detection of the primary tumor (Table 2) PET with fluorine-18-fluorodeoxyglucose was performed. Results: Due to the PET result a primary tumor was suggested in 31/52 patients (60%), and confirmed in 21/52 patients (40%). In 16/43 patients (37%) with initially (before PET) localized disease dissemination was detected by PET only, despite various preceding diagnostic procedures (Figure 1). Overall, in 33/52 patients (63%) the PET result had major impact on selection of an individual treatment (Table 3), in case of initially localized disease in 30/43 patients (70%). Conclusion: In patients with CUP the PET result is not only of great value for detection of the primary tumor, but in case of initially tocalized disease also for diagnosis of a possible dissemination. The PET result often has relevant influence on therapeutic management.