The value of positron emission tomography (PET) for therapeutic managementin patients with cancer of unknown primary (CUP)

Background: In patients with cancer of unknown primary median survival for Localized disease is 20, for disseminated disease 7 months. After diagnosti c procedures including MRI or endoscopy, the primary tumor is detected in L ess 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 r elated to therapeutic regimens. Patients and Methods: Between May 1998 and February 2001 a total of 52 pati ents with CUP syndrome, 18 females and 34 males, have been included. At fir st diagnosis, stage of disease was localized in 43 patients (35 lymphonodal , eight visceral), and disseminated in nine patients (Table 1). After a med ian of seven (range three to eleven) diagnostic procedures without detectio n of the primary tumor (Table 2) PET with fluorine-18-fluorodeoxyglucose wa s performed. Results: Due to the PET result a primary tumor was suggested in 31/52 patie nts (60%), and confirmed in 21/52 patients (40%). In 16/43 patients (37%) w ith initially (before PET) Localized disease dissemination was detected by PET only, despite various preceding diagnostic procedures (Figure 1). Overa ll, 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 localized dise ase also for diagnosis of a possible dissemination. The PET result often ha s relevant influence on therapeutic management.