Preoperative Prediction of Pathologic Response to Neoadjuvant Chemoradiotherapy in Patients With Esophageal Cancer Using 18 F-FDG PET/CT and DW-MRI: A Prospective Multicenter Study.

Purpose: Accurate preoperative prediction of pathologic response to neoadjuvant chemoradiotherapy (nCRT) in patients with esophageal cancer could enable omission of esophagectomy in patients with a pathologic complete response (pCR). This study aimed to evaluate the individual and combined value of ¹⁸ F-fluorodeoxyglucose positron emission tomography with integrated computed tomography ( ¹⁸ F-FDG PET/CT) and diffusion-weighted magnetic resonance imaging (DW-MRI) during and after nCRT to predict pathologic response in patients with esophageal cancer.
Methods and Materials: In this multicenter prospective study, patients scheduled to receive nCRT followed by esophagectomy for esophageal cancer underwent ¹⁸ F-FDG PET/CT and DW-MRI scanning before the start of nCRT, during nCRT, and before esophagectomy. Response to nCRT was based on histopathologic evaluation of the resection specimen. Relative changes in ¹⁸ F-FDG PET/CT and DW-MRI parameters were compared between patients with pCR and non-pCR groups. Multivariable ridge regression analyses with bootstrapped c-indices were performed to evaluate the individual and combined value of ¹⁸ F-FDG PET/CT and DW-MRI.
Results: pCR was found in 26.1% of 69 patients. Relative changes in ¹⁸ F-FDG PET/CT parameters after nCRT (Δ standardized uptake value [SUV] _mean,post P = .016, and Δ total lesion glycolysis _post P = .024), as well as changes in DW-MRI parameters during nCRT (Δ apparent diffusion coefficient [ADC] _during P = .008) were significantly different between pCR and non-pCR. A c-statistic of 0.84 was obtained for a model with ΔADC _during , ΔSUV _mean,post , and histology in classifying patients as pCR (versus 0.82 for ΔADC _during and 0.79 for ΔSUV _mean,post alone).
Conclusions: Changes on ¹⁸ F-FDG PET/CT after nCRT and early changes on DW-MRI during nCRT can help identify pCR to nCRT in esophageal cancer. Moreover, ¹⁸ F-FDG PET/CT and DW-MRI might be of complementary value in the assessment of pCR.
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