Fluorine-18-Fluorodeoxyglucose Positron Emission Tomography for Interim Response Assessment of Advanced-Stage Hodgkin's Lymphoma and Diffuse Large B-Cell Lymphoma: A Systematic Review

To systematically review the prognostic accuracy of fluorine-18-fluorodeoxyglucose positron emission tomography (FDG-PET) for interim response assessment of patients with untreated advanced-stage Hodgkin's lymphoma (HL) or diffuse large B-cell lymphoma (DLBCL). MEDLINE, EMBASE, SCOPUS, and Biologic Abstracts were searched for relevant studies. Two assessors independently reviewed studies for inclusion and extracted data. Relevant unpublished data were requested from the investigators if unavailable from publications. A meta-analysis of the prognostic accuracy was performed. Thirteen studies involving 360 advanced-stage HL patients and 311 DLBCL patients met our inclusion criteria. Advanced-stage HL studies included few unfavorable-risk patients. DLBCL studies were heterogeneous. FDG-PET had an overall sensitivity of 0.81 (95% CI, 0.72 to 0.89) and a specificity of 0.97 (95% CI, 0.94 to 0.99) for advanced-stage HL, and a sensitivity of 0.78 (95% CI, 0.64 to 0.87) and a specificity of 0.87 (95% CI, 0.75 to 0.93) for DLBCL. Meta-regression and subgroup analyses did not identify factors that affect prognostic accuracy. For low- to intermediate-risk advanced-stage HL, FDG-PET performed after a few cycles of standard chemotherapy seems to be a reliable prognostic test to identify poor responders, warranting prospective studies to assess PET-based treatment strategies. For DLBCL, no reliable conclusions can be drawn due to heterogeneity. Interim PET remains an unproven test for routine clinical practice. Its use should be reserved for research settings where treatment regimens and imaging conditions are standardized.