Added value of baseline 18F-FDG uptake in serial 18F-FDG PET for evaluation of response of solid extracerebral tumors to systemic cytotoxic neoadjuvant treatment: a meta-analysis.
The purpose of this study was to test the hypothesis that the level of baseline (18)F-FDG uptake in the primary tumor adds value to its relative change in (18)F-FDG uptake in serial PET scans in predicting the histopathologic response to systemic cytotoxic neoadjuvant treatment of patients with solid extracerebral tumors.


METHODS
We performed a literature search from January 1995 through November 2008 using PubMed and Embase. Two reviewers independently selected eligible studies for possible inclusion in the meta-analysis by reviewing titles and abstracts. Inclusion criteria were at least 10 patients, (18)F-FDG PET before and after therapy, (18)F-FDG PET performed with the intention of monitoring the response of solid extracerebral tumors in humans to cytotoxic neoadjuvant systemic therapy, attenuation-corrected (18)F-FDG PET studies, and studies presenting individual patient data (PET results and histopathologic reference test after treatment). Multilevel logistic regression was used to assess the effect of relative change of (18)F-FDG uptake ([baseline - end]/baseline) and baseline (18)F-FDG uptake value with type of tumor and type of treatment as level 1 covariates.


RESULTS
Nineteen studies (all observational; a total of 438 patients [median, 23 patients per study; range, 10-40]) were included, aiming at the accuracy of PET versus histopathology. To quantify PET, maximum standardized uptake value (SUV) was used in 6 studies, mean SUV in 7, SUV (subtype unclear) in 1, tumor-to-background ratio in 3, and dose uptake ratio in 1. The average overall histopathologic response rate was 0.47 (median, 0.50), ranging from 0.17 to 0.88. The relative change in (18)F-FDG uptake was the strongest indicator (P < 0.0001) for tumor response. Baseline (18)F-FDG was not significantly associated as a main factor; however, a significant interaction of baseline uptake and relative change after therapy was observed (P < 0.001).


CONCLUSIONS
Relative change in (18)F-FDG uptake was the strongest indicator for tumor response, but the level of baseline (18)F-FDG uptake in the primary tumor provided additional information about prediction of response to therapy. These data corroborate and extend the need for standardization, quality assurance, and control of PET studies quantifying (18)F-FDG in oncologic treatment monitoring.
Quarles van Ufford
Henriëtte M E
HM
Department of Radiology and Nuclear Medicine, University Medical Center Utrecht, Utrecht, The Netherlands. h.m.e.quarlesvanufford@umcutrecht.nl
van Tinteren
Harm
H
Stroobants
Sigrid G
SG
Riphagen
Ingrid I
II
Hoekstra
Otto S
OS
D000970:Antineoplastic Agents / Q000627:therapeutic use*; D019788:Fluorodeoxyglucose F18 / Q000493:pharmacokinetics; D006801:Humans; D020360:Neoadjuvant Therapy; D009369:Neoplasms / Q000000981:diagnostic imaging* / Q000188:drug therapy* / Q000378:metabolism; D049268:Positron-Emission Tomography / Q000706:statistics & numerical data*; D011379:Prognosis; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D016896:Treatment Outcome
D000970:Antineoplastic Agents; D019788:Fluorodeoxyglucose F18