Nucl Med Mol Imaging.  2014 Dec;48(4):295-302. 10.1007/s13139-014-0289-x.

Tumor SUVmax Normalized to Liver Uptake on 18F-FDG PET/CT Predicts the Pathologic Complete Response After Neoadjuvant Chemoradiotherapy in Locally Advanced Rectal Cancer

• Park J
• Chang KJ
• Seo YS
• Byun BH
• Choi JH
• Moon H
• Lim I
• Kim BI
• Choi CW
• Lim SM

• KMID: 2313212
• DOI: http://doi.org/10.1007/s13139-014-0289-x

Abstract

PURPOSE
This study investigates the feasibility of using 18F-fluorodeoxyglucose positron emission tomography/computed tomography (18F-FDG PET/CT) to predict the pCR (pathologic complete response) rate after neoadjuvant chemoradiotherapy (NCRT) in patients with locally advanced rectal cancer.
METHODS
A total of 88 patients with locally advanced rectal cancer were retrospectively analyzed. All patientswere treated with NCRT, followed by radical surgery, and 18F-FDG PET/CT was performed before and after NCRT. For a semiquantitative assessment, a volume of interest was drawn, including the whole tumor region, and the maximum SUV (SUVmax), SUVmax normalized to liver uptake (SLR), SUVmax normalized to blood pool uptake (SBR), the metabolic tumor volume at SUV 2.0 (MTV[2.0]), SUV 2.5 (MTV[2.5]), and SUV 3.0 (MTV[3.0]) were measured. In addition, their percentage changes after NCRT were assessed. The pCR was verified through a histologic examination of postsurgical specimens.A receiver operating characteristic curve analysis was conducted to predict the pCR by using these PET parameters.
RESULTS
The pCR was predicted in 17 patients (19 %). The values of the area under the curve (AUC) for predicting the pCR were 0.774 for SUVmax after NCRT, 0.826 for SLR after NCRT, 0.815 for SBR after NCRT, 0.724 for MTV(2.5) after NCRT, 0.729 for the percentage change in SUVmax, 0.700 for the percentage change in SLR, and 0.749 for the percentage change in MTV (2.5). Among these PET parameters, SLR after NCRT showed the highest AUC value. The optimal criterion, sensitivity, specificity, and accuracy of SLR after NCRT for predicting the pCR were < or =1.41, 88 %, 65 %, and 68 %, respectively.
CONCLUSION
F-FDG PET was found to be useful for predicting the pCR after NCRT in patients with locally advanced rectal cancer. Among various PET parameters, SUVmax normalized to liver uptake after NCRT was the best predictor of the pCR.

Keyword

Rectal Cancer; Chemoradiotherapy; Response; 18F-FDG; Positron emission tomography

MeSH Terms

Area Under Curve
Chemoradiotherapy*
Electrons
Fluorodeoxyglucose F18*
Humans
Liver*
Polymerase Chain Reaction
Positron-Emission Tomography
Positron-Emission Tomography and Computed Tomography*
Rectal Neoplasms*
Retrospective Studies
ROC Curve
Sensitivity and Specificity
Tumor Burden
Fluorodeoxyglucose F18