Clinical value of FDG-PET for therapy monitoring of malignant lymphoma - Results of a retrospective study in 72 patients

Aim of the present retrospective study was to validate the clinical value o f FDG-PET for therapy control of malignant lymphoma. Method: 72 patients (4 1 non-Hodgkin lymphomas, 29 Hodgkin's disease, 2 unclassified) received sta tic FDG-PET scans of initially involved regions (n = 53) or of the entire n eck and trunk (n = 19) after therapy. CT imaging (n = 70) and serum LDH mea surement (n = 64) were also performed. Results were validated either by bio psy (n = 7) or by clinical follow-up (n = 65). The predictive value of PET was analysed in relation to different prognostic factors (stage, recurrence status, number of prior therapy regimen). Results: PET obtained a sensitiv ity oi 88%, a specificity of 83% and an overall accuracy of 85% for detecti on of residual disease. The values for CT were 84%, 31% resp. 54%, and for serum LDH 50%, 92% and 73%. The predictive value of PET was related to the prevalence of residual disease. PET predicted complete remission in more th an 90% of patients with moderate risk (stage I-III, no relapse, no more tha n two different therapy regimens). In high risk patients, however, the nega tive predictive value of PET was 50-67%, Conclusion: FDG-PET is more accura te than CT imaging and LDH measurement for therapy monitoring of malignant lymphoma. Therapy success can be reliably predicted in patients with modera te risk.