Background. We conducted a systematic review and meta-analysis to better define the prognostic ability of fluorine-18-fluorodeoxyglucose positron emission tomography (18F-FDG PET) following salvage chemotherapy for relapsed or refractory Hodgkin's lymphoma (HL) and aggressive non-Hodgkin's lymphoma. Methods. We searched PubMed (from inception to January 31, 2010), bibliographies, and review articles without language restriction. Two assessors independently assessed study characteristics, quality, and results. We performed a meta-analysis to determine prognostic accuracy. Results. Twelve studies including 630 patients were eligible. The most commonly evaluated histologies were diffuse large B-cell lymphoma (n = 313) and HL (n = 187), which were typically treated with various salvage and high-dose chemotherapy regimens. Studies typically employed nonstandardized protocols and diagnostic criteria. The prognostic accuracy was heterogeneous across the included studies. 18F-FDG PET had a summary sensitivity of 0.69 (95% confidence interval [CI], 0.56-0.81) and specificity of 0.81 (95% CI, 0.73- 0.87). The summary estimates were stable in sensitivity analyses. In four studies that performed direct comparisons between PET and conventional restaging modalities, PET had a superior accuracy for predicting treatment outcomes. Subgroup and metaregression analyses did not identify any particular factor to explain the observed heterogeneity. Conclusion. 18F-FDG PET performed after salvage therapy appears to be an appropriate test to predict treatment failure in patients with refractory or relapsed lymphoma who receive high-dose chemotherapy. Some evidence suggests PET is superior to conventional restaging for this purpose. Given the methodological limitations in the primary studies, prospective studies with standardized methodologies are needed to confirm and refine these promising results.
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