FDG-PET/CT imaging predicts histopathologic treatment responses after the initial cycle of neoadjuvant chemotherapy in high-grade soft-tissue sarcomas

Matthias R. Benz, Johannes Czernin, Martin S. Allen-Auerbach, William D. Tap, Sarah M. Dry, David Elashoff, Kira Chow, Vladimir Evilevitch, Jeff J. Eckardt, Michael E. Phelps, Wolfgang A. Weber, Fritz C. Eilber

Research output: Contribution to journalArticlepeer-review

158 Scopus citations

Abstract

Purpose: In patients with soft-tissue sarcoma (STS), the early assessment of treatment esponses is important. Using positron emission tomography/computed tomography (PET/CT) with [ 18F]fluorodeoxyglucose (FDG), we determined whether changes in tumor FDG uptake predict histopathologic treatment responses in high-grade STS after the initial cycle of neoadjuvant chemotherapy. Experimental Design: From February2006 to March 2008, 50 patients with resectable high-grade STS scheduled for neoadjuvant therapy and subsequent tumor resection were enrolled prospectively. FDG-PET/CT before (baseline), after the first cycle (early follow-up), and after completion of neoadjuvant therapy(late follow-up) was done. Tumor FDG uptake and changes were measured by standardized uptake values. Histopathologic examination of the resected specimen provided an assessment of treatment response. Patients with ≥95% pathologic necrosis were classified as treatment responders. FDG-PET/CTresults were compared with histopathologic findings. Results: At early follow-up, FDG uptake decreased significantly more in 8 (16%) responders than in the 42 (84%) nonresponders (-55% versus -23%; P = 0.002). All responders and 14 of 42 nonresponders had a ≥35% reduction in standardized uptake value between baseline and early follow-up. Using a ≥35% reduction in FDG uptake as early metabolic response threshold resulted in a sensitivity and specificity of FDG-PET for histopathologic response of 100% and 67%, respectively. Applying a higher threshold at late follow-up improved specificity but not sensitivity. CT had no value at response prediction. Conclusion: A 35% reduction in tumor FDG uptake at early follow-up is a sensitive predictor of histopathologic tumor response. Early treatment decisions such as discontinuation of chemotherapy in nonresponding patients could be based on FDG-PET criteria.

Original languageEnglish
Pages (from-to)2856-2863
Number of pages8
JournalClinical Cancer Research
Volume15
Issue number8
DOIs
StatePublished - 15 Apr 2009
Externally publishedYes

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